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208 Cards in this Set
- Front
- Back
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define Biostats
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stats that applies statistical methods to medical and biological phenomena
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define stats
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methods or procedures that ppl apply to understand data
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define research
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field of disciplined investigation
-SYSTEMIC IDing of relationships and/or differences among groups |
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3 Types of Research
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Basic
Applied Developmenttal |
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Basic Research does what
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Gathers data
develops NEW theory no practical application |
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what drives basic research?
what is the goal |
driven by curiousity or interest in a scientific question
Goal:Expand man's knowledge |
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Applied Research applies..
develops... |
applies a model or theory
can develop a NEW theory |
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Applied Research
designed to? Goal |
designed to solve practical problems
Goal-IMPROVE the human condition |
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Developmental Research
define? used for? |
its the development of a PROJECT
-problem oriented -interdisciplinary |
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developmental Research
-Goal? -does it create a new theory? |
Goal-DEVELOPs prototype products
-maybe theory driven, but DOES NOT result in NEW theory |
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Where can you find research topics?
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self-anaylsis-own's interest
interview experts literature reviews reference lists-suggests direction |
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factors to consider when selecting research topic?
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own interests
don't duplicate avoid person bias/prejudice is it achievable? usefulness? resources available? |
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Components of Research project
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A. IOMR DLC RA
think about it-not typin it out |
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Abstract is...
components? |
summary of study
usually <250words -Obj, Methods, Results, Conclusions, Key Words |
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Introduction
-breakdown of this section.. |
A.statement of problem-ID it
B. Literature Review |
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Introduction
statement of problem, break this down |
1.ID the problem-describe effects on popuation
2.Backgroun and origin of problem-what reader needs to know 3.Rationale-benefits, main findings from others, goals, knowledge gaps 4.Importance of it-effects.implications, applications |
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Introduction
B.Literature Review, break this down |
1.Critical analysis of related
-curent knowledge of topic -show study is based on older research 2.Compare/contrast diff study |
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Objective
-what does it ask? |
what do you want to FIND OUT?
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Methodology
-break it down |
A.Hypotheses,research ?'s
B. Study Design C.Study Setting and sample selection D.Instrument E.Procedure F. Statistical Analysis |
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Methodology
-B. Study setting and sample selection, what does it indicate |
Indicates location of study, explain why u chose
Describe partcipants -socio-demographic |
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Methodology
C.Instrument |
Why did you choose it?
Purpose and content of instrument -if used other instruments source-cite validation /reliability If developed-explain develop., valid, and reliab. Explain how to interpret it |
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Methodology
E.Procedure |
1.detail procedure to admin instrument
2.If, pilot study-show procedures/results/impact 3.Indicate duration of stages 4.Indicate any measures to gurantee quality |
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Methodology
F.Statistical Analysis |
1.Which stats going 2 use
2.Why you chose it 3.Which software using to analyze data and version |
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Results
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Describe findings-use tables, figures
-Facts ONLY Free from interpreting,evaluating |
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Discussion
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1.Discuss results-related to hypotheses-research ?'s
2.Compare/contrast from old studies 3.Discuss effects of uncontrollable variables 4.Discuss each result compared to old studies |
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Limitations
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Factors that may have an EFFECT on findings
-limited sample size -Socially acceptable responses |
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Conclusions/Reccommendations
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So what?
discuss implications of study state reccommendations for future |
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References
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Only sources discussed in txt
verify referencing style needed |
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Appendices
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extract info, data, and figures
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Concept
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label for an ABSTRACTidea
-objects/events that share common characteristics and common name ex-chair n sofa |
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Constructs
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highly abstract concepts
ex-anxiety,leadership |
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Define model
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representation of reality
-replica of complex phenomenon shown in visual format |
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Paradigm
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Set of assumptions, concepts, values and practices that constitutes a way of viewing reality
-ideal way of explaining |
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Variables
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qualities and or characteristics of persons,studied in research
-concepts concretely defined |
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Research Variables
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qualities/characterisitics in research problems-that are to be identified or MEASURED in study
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Types of Research Variables
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Independent
Dependent Confounding Attribute |
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Independent Variable
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activity that is manipulated to cause effect on dependent variable
-used to classify data-like genders |
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Independent Variables
AKA |
treatment or experimental variable
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Dependent Variable
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response/outcome that researcher wants to predict or explain
-change caused by independent |
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Dependent Variable
AKA |
Effect variable
criterion measure |
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as independent variable is changed, rsearcher observes changes in....
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the dependent variable...(moron) and hows its associated with changes in independent
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Confounding Variables
-define -AKA |
can AFFECT measurement of study variables
-aka, extraneous, uncontrolled |
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example of confounding
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AGE
-study shows ppl with type 2 diabetes 4x more like to get dementia -study had old ppl-well old ppl more likey to have dementia....confuses stats |
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Attribute Variables
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characteristics of human subject collected to describe the sample
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Attribute Variables
AKA |
Demographic variables
-age, gender, income, race, jobs |
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Operationalizing the Variables
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developing of conceptual def and operational def
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what is the conceptual definition
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broad, abstract meaning of a concept
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what is the operational definition
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explanation of how the variable will be measured
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Data
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information in NUMERICAL form
-constant -variable |
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Data
-define constant |
same characteristic for every member of the group
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Data
-define variable |
characteristic has different values for different members in group
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Descriptive stats
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used to classify and SUMMARIZE numerical data
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Inferential stats
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generalizations bout population from studying the sample of population
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Define population or universe
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all members of a specified group
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define sample
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a subset of a population
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characteristics of population are called..
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parameters
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how are parameters represented?
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greek letters
ex mean of population=mu |
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characteristics of sample are called
represented with.. |
estimates
with Roman letters mean of sample= x (bar over it) |
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we draw conclusions about characteristics of _________ based on corresponding characteristics of _____
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population
based on sample |
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Observational Study Design
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design where investigators collect,record, and analyze data on subjects as they naturally divide themselves by significant variables
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T or F
Human intervention is not a part of the process |
True
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2 types of observational studies
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1. Descriptive Studies
2. Analytic Studies |
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Descriptive studies
-focuses? |
focus-describes what already exists
focus on characterizing the occurence of condition/problem by person/place/time -No a priori hypotheses(wtf?) |
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examples of Descriptive studies
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case reports-case series
cross sectional |
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what is a case report
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description of interesting characteristics sceen in 1 patient
-unusual or rare conditions |
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what is purpose of case reports
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introduces audiences to new information bout drug and clinical outcome
-cannot test hypotheses |
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what is the weakest observational study design
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descriptive studies-case reports
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what is a case series
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extension of case report
-describes characteristics of group or cluster with SAME disease |
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adv vs disadv of case-series
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adv-easy to write,help to generate hypotheses
disadv-could be biased-subject selection, characteristic sceen can't reach conclusions |
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what is a cross-sectional study
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analysis of data for group of ppl at ONE POINT in time
-what is happening right now |
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other names of cross-sectional studies
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prevalence study, surveys, epidemiologic study
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cross-sectional studies are considered...
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"snapshots" of whats happening at a certain moment
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adv of cross-sectional studies
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adv-useful for determing status quo of disease
-evaluate diagnostic procedures |
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disadv of cross-sectional studies
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only shows "snapshot" in time of disease
-can result in misleading information |
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examples of analytic studies
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cross-sectional
ecologic multi-level analysis case control cohort hybrid |
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cross sectional is in descriptive or analytic studies?
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its in both
if only stating a problem=descriptive if making a hypothesis=analytic |
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what is ecologic or aggregate analysis?
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analyzes focusing on comparisons of GROUPS
Groups derived from geographic area or time periods(ecological unit) |
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examples of ecologic
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city, country, state, month, year, decade
summary measures are for the entire population in each ecologic unit |
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ecologic look at?
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aggregated data; such as percentages, rates and means
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advantages of ecologic analyses
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inexp., quick,
Generate hypotheses Avoid measurement limitations Ideal for evaluation of the population effect of public policies,programs and legisl. |
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limitations of ecologic analyses
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ecologic fallacy
-ecologic analysis fails to reflect biologic effects at individual level -Overall correlations can mask important differences in subgroups(large pop does this) |
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Multi-level analyses
define- -helps to assess what? |
individual level analyses that incorp some ecologic measurements
if individuals health is shaped by group-level variables(family income) or population characteristics(pop. density) |
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what is case control
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comparison of cases of the disease being investigated with a comparable group of controls
-matched pair or unmatched pair designs |
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Case control
subjected selected on what basis? |
of wether they have or do not have the disease
compares exposure histories moves from effect to cause |
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matched pair design
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used to control for confounding and selction bias
can increase statistical power |
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matched pair designs
whats it used for |
for rare diseases, NOT rare risk-factors
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advantages of case control
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usefu for RARE diseases, conditions developing over long time, investigating prelim. hypothesis
multiple potential risk factors |
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whats the least expensive study
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case control studies
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disadvantages of case control studies
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not for rare risk factors!
difficult to ID comparable cases & controls |
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selecting controls for case-control studies
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must be a sample of the population that produced the cases
-exposed &unexp controls have same prob of being selected |
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Sources of case ID
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hospital/clinic pt rosters
death cert's special surverys-National Health and Nutrition Exam Survey Special reporting systems-cancer registries |
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Sources of ontrol ID
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Population controls(preferred)
hospital or clinic controls dead controls |
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Source of Control ID:population
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tax lists
voter registration random digit dialing |
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Population source
advantages |
make sure controls and cases come from same population
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population source
disadvantages |
time consuming
Expensive to ID Recall of risk factors of healthy ppl may be limited |
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Hospital/clinic source
adv. |
easy ID
good participation rates less exp to ID |
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Hospital/clinic source
disadvantages |
difficult to determine appropriate illness for inclusion
-pts usualy have multiple co-morbidities |
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Source of Control ID; Dead Controls
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Not recc. cause they may not rep. source pop. that producted the cases
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Source of control ID;friends, spouse, and relative controls
Advantages |
sibilings share genetic traits
share-race, education, socioeco status |
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Source of control ID:friends
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difficult to find
controls may share habits(bias) |
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Sources of Exposure
Information |
in person & phone convos
self administered questionares |
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cohort studies
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used to study the risk of developing a disease
risk factor/exposure is determined BEFORE outcome/disease |
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definition of cohort
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group of individuals who are followed over time
done when intentional exposure to humans isnt justified |
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cohort studies
-how are subjects selected? |
by some defining characteristic suspected of being a RISK factor for a disease
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Cohort studies
direction? answers what question? also called? |
direction-foward in time
question-What will happen AKA-prospective studies ex-framingham study |
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define types of population of cohort studies
open |
subjects allowed to enter the study at VARIOUS time after started
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define types of population of cohort studies
closed |
no subjects can be added to the study after it has started
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define types of population of cohort studies
fixed |
when cohort is formed on basis of irrevocable event;medical exposure
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Prospective cohort study
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exposure status of pts is determined at start of study, before any disease/outcome has occured
-pt followed into future |
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Retrospective/historical cohort study
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outcome/disease already occured
cohort is traced from that time up to the present |
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advantages & disadv of retrospective cohort study
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cheaper than prospective, easier
more risk for confounding & bias than prospective |
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what is ambidirectional cohort study
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combines components of prospective and retrospective cohort studies
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Sources of info on exposure for cohort studies
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med & employment records
lab tests interviews -data can be preexisting OR designed for the study |
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Cohort studies
advantages |
evaluation of multiple outcomes
-rare exposures |
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cohort studies
disadvantages |
large sample sizes
loss to follow up bias exposure/outcome misclassified(confounding) |
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case control vs cohort
direction? |
cc-outcome to risk factor
cohort-risk factor to outcome |
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case control vs cohort
diseases? |
cc-Rare
Cohort-High incidence |
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Hybrid studies
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Nested case-control
-nested case-cohort panel study repeated surveys |
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nested case-control study
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involves case-control study in cohort study
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how are cases/controls developed in Case-control study
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develop dis-Case
cohort /\ v dont devel-control |
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nested case-cohort study
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variation of nested case-control study
-selected randomly ppl who get disease sorted out during analysis |
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Panel Study
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combines Cross sectional and prospective cohort
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what is the panel
what are waves? |
panel-same subjects have series of cross-sectional studies conducted on them
waves-at successive time intervals |
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what is repeated surveys
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successive cross-sectional studies over time on same study popul., but each sample is independently selected
same pop, diff sample each time |
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meta-analyses
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combines results of 2 or more indiv. studies into 1
then evaluates them statistically |
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objectives of meta-analyses
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increase stat power by inc. SAMPLE SIZE
improves estimates of effect size answers questions not posed at beginning of study |
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how meta-analyses combine results
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determine effect then combines any of: z approximation(proportions)
ttest(means) p values(comparisons) odds ratio with conf. intervals |
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in meta-analyse what numbers are combined
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p value(overall ) or confidence interval
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what be determined and when for meta-analyses
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inclusion/exclusion criteria
and must be before the analysis |
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meta-analysis, data extraction, what should be done to avoid bias
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least 2 individuals must gathers data indep. and then reconcile
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strengths/benefits of meta-analysis
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give supporting evidence for clinical decison making
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limits of meta-anaylsis
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publication bias
heterogeneity can affect reliability controversy of unpub. data included |
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define bias
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systematic error in design/conduct giving false association btwn exposure and disease
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what is publication bias
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bias towards likelihood to be published
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how to minimize publication bias
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incluse published and unpub. data
search multiple databases |
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what is selection bias
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choose subjects that give result that is different from result that would occur mong individuals who coulda been studied
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what is performance bias
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systematic differences in the care to ppl in different tx groups
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how to minimize performance bias
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blinding/masking
keep group assignment a secret from particpants and investigators |
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what is detection bias
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riskfactor leading to inceased diagnostic investigations and increase the prob. that the disease if IDed in subet
ex-breast cancer idea |
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Attrition Bias
AKA |
subjects no longer want to do study/can't be located
aka-loss to follow up |
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ways to minimize attrition bias
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collection of info to help locate ppl in study-social, DOB
send newletters |
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meta-analysis:stats
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ID if data is hetero or homogenous
larger studies-given more weight |
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what are the sources of heterogeneity
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chance
variations in pts and interventions diff outcome measures |
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what is I(squared) statistic
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%of variation across the studies that arnt cause of chance
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what does I2 measure
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magnitude of heterogeneity
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what are ranges of heterogeneity
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<25% LOW hetero
25-75% moderate hetero >75% high |
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sources of meta-analysis
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cochrane handbook
-paper, CDrom,and internet |
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define cumulative meta-analysis
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refers to repeated performance of meta-analysis in chronological fashion
-its an update of existing metas with new data |
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when is cum. meta useful
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clear consensus doesn't exist
continuous generation of data |
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Quasi-Experimental research
AKA used for? |
nonrandomized PRE & POST intervention studies
when not feasible to do RCT to give benefits of interventions try to draw conclusion bout a particular procedure/Tx |
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quasi experiment
strong or weak? |
considered weak
-do not prevent bias in pt assignment |
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what is most common quasi experimental
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nonequivalent group design
-lacks random assignment |
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Experimental studies
key? AKA? |
key-assignment of pts is under control of researcher
AKA-intervention studies, Trials |
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how are experimental studies classified
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controlled trials
uncontrolled trials |
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how are the controlled trials of experimental studies classified
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1. parallel or concurrent controls-random/nonrand
2.Sequential controls-selfcontroled, crossover 3.External controls(historical) |
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Controlled Trials
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experimental drug/procedure compared with another drug/procedure or placebo
-greater validity |
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methods to control trials
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concurrent control
double blind trials blind trials |
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what is concurrent control
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interventions for both groups for same time period in same study
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doub blind trials
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researchers/pts know which group is tx or control
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blind trial
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subject is unaware of tx or control group
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which trial is the gold standard
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Randomized Clinical Trials
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RCT's
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pts assigned to diff tx groups by chance
strongest evidence for concluding CAUSATION |
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why are RCT's gold standard
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tight control of experimental cond. and randomization of subjects
results can be replicated by investigators who use same study protocol |
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types of RCT's
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preventive/prophylactic trials-primary prev.-vaccines
intervention trials-secondary-drugs therapeutic trials-tertiary prev-efficacy of diff forms for cancer tx |
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advantages of RCTs
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establish efficacy of tx
investigators control level of exposure |
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disadvantages of RCTs
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can be taken advantage of by manu(nonrandomized studies show pos outcomes)
expensive long duration |
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more disadvantages of RCTs
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artifical settings-may not represent real world
-may have limited external validity |
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Randomization
define works best when? |
where pts have same probability of being in either group
works best in large samples >100 |
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permuted block
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gen. an allocation sequence of assignments based on a block
if allocation ratio of block of 20 is 3:1-block is 15x &5y |
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stratification
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useful if characteristic or prognostic factor is important to analysis
-gender, ethnicity, age |
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nonrandomized trials
AKA |
clinical trials or comparative
considered weaker, don't prevent bias it pt assignment |
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define self controlled studies
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uses pt's as their own controls
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limitations of self controlled study
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hawthrone effect
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what is the hawthorne effect
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pt change behavior and imporve cuz they recieve special attention by being in study/not cuz study intervention
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describe the crossover study
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combo of concurrent and self controlled studies
start with 2 groups-washout-then switch groups |
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what does the crossover study test
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tests one hypothesis
examines effect withinand between groups being compared |
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advantages of crossover
disadvantages |
more statistical power
attrition rate ionly for nterventions that provide temp relief |
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what are external controls
examples |
controls external to study-used to compare differences
historical controls |
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define historical controls
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pts the investigator has treasted in past
used for incurable diseases |
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what are uncontrolled trials
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investigators experience with drug but tx is not compared with another tx
used more for procedures |
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disadvantages of uncontrolled trials
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assumption procedure used is best one
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community trials
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unit of analysis are groups of ppl or community
test etiologic hypotheses |
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disadvantages of community trials
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differences may be due to causes other than the intervention
expensive |
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control group
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subjects recieve no intervention or one where they recieve standard or conventional intervention
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when do scientific discoveries first exist?
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when they are published
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what is the declaration of Helskinki, Principle 27
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Authors and publishers have ethical obligations
They are obligated to keep results accurate. Neg or Pos should be published |
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what are the imperatives of public dissemination
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judgement that meets required scientific and social value
justification avoidance of publication bias participants entitles to know results |
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whos resposible for ascertainment of the dissemination of results
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IRB
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what must be clearly establed for acertainment of dissemination
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authorship
-name of investigator -contact info -affiliations |
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why should be siddeminate research findings
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social responsibility
research promotin education |
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what is a consort and what does it regulate
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consolidated standards of reporting trials
regulates the results reported of randomized clinical trials |
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a consort statement is broken down into...
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check list and flow chart
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what is flowchart
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progess of pts throughout trial
periodic updates |
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what is a checklist
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25 items
dsign, analysis, and interpretation of results |
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define extensions
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add;l consideration that addresses other models of randomly control trials
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examples of extensions
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non-pharm interventions
herbal-interviewing non-inferiority equivalence trials |
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examples of dissemination of research results
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abstracts
Journal Articles Poster presentations |
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dissemintation ex
abstract |
summary or research findings
structed format -into, method, result,discuss, andconclusions |
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dissemination ex
journal articles |
primary lierature only
rigorous peer review process timeline is CRUCIAL |
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dissemination ex
newletterss |
short articles
for fast dissemination Easy to read format |
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dissemination ex
web postings |
immediate disseminator of info
reputable ex-gov, org, edu |
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Poster presentation
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written display or results
mix of tables, figures, pics, graphs |
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characteristics of high quality poster presentation
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accuracy of results
correctness clarity |
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Poster tips
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should be easily read at a distance of 4 feer(font size no larger than 18)-should be 24
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Poster presentation
Artistry is...... |
NOT subsitute for content
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what is key in poster presentation
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grammar
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responsible dissemination of research is
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fundamental to communicate new findings and cencourage the promotion worldwide
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sharing of new knowledge is
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longstanding norm in the scientific community-moral obligation
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