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87 Cards in this Set

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  • Back
rates ratios and proportions often measure...
dichotomous outcomes
rates, rations and proportions are what type of measures?
descriptive measures
rate is..
frequency of event in specific time period
what does finding risks for different subgroups allow for
allows identification of high risk groups and possible clues of causality
4 components of rate
numerator- freq
denominator- population
time period
multiplier - / how many
ratio is...
relationship between numerator and denominator when they are unconnected quantities
proportion is...
numerator and denominator are always related

often shown as percent
rate- X / delta t

ratio- X / Y

proportion- X / Y+X
any departure from well being
any departure from actually living...aka death
morbidity measures are?
incidence and prevalence
number of new cases
number of cases in population
Cumulative incidence is
proportion of population at risk that develops disease over specific peroid

denominator must be observed entire duration followup
Cumulative incidence equation is
CI = number new cases dx during time
Pop at risk during same time
Incidence rate is
same shit only with diff length of folow up times
Incidence rate equation
Numberof new cases in specific time
IR = __________________________
total person time of observation in pop at risk...huh
Prevalence is
number of existing cases in entire pop
point prevalence is
number of ppl w/ dx at single point in time
total number pop at that time
period prevalence is
number ppl w/ disease at any point during time peroid
number of persons in pop
incidence and prevalence

think about it as...
a bath tub....
incidence water going in
prevelence water inside
and death or recovery is how fast water leave and prevelance goes down
Crude mortality rate is

total number deaths from all causes per 1000 persons during specific time
total number persons at that time
Age specific mortality rate is

total number of deaths from all causes in specific age group
total number in that age group
Cause specific mortality rate

deaths from specific cause
total pop that period
case fatality

propensity of disease to cause death

number deaths from dx
# ppl w/ dx
proportionate mortality
proportion of deaths from specific cause

deaths from dx
total deaths
Association measuring is
statistical relationship tween 2 or more variables
Exposure vs Outcome
exposure- potential causal characteristics (behavior or tx)

outcome- consequence of behavior or tx
how do we measure association
risk ratio

odds ratio
risk ratio is
risk of developing event in exposed individual to that of unexposed individual

cumulative incidence exposed
cumulative incidence unexposed
risk ration of 1 means?

when does exposure show association?
-risk is equal in exposed and unexposed groups

-if greater than 1 than exposure is associated

NOTE TO REMEMBER- for calculations with risk ratio recognize that total is for each group not whole study!!!!
Odds ratio is..
ratio of number events and nonevents in cases to number of events and nonevents in control....

double positives * double negative
mixed * mixed
OR greater than 1 means?

what about less?
greater- odds for event in exposed group higher

less- event less liekly in exposed group
Difference in descriptive and analytic epidemiology?
analytic- tests predetermined hypotheses about association tween exposure and outcome variables
hypothesis serves as
framework for determining statistical significance
null hypothesis...
really how many times have we learned this now....

means no difference (for u morons out there)
alternative hypothesis..
theres an association
When type 1 and type 2 errors?

wheres beta and alpha?

?]]when does power matter?
I = P = positive

II = N = negative

power matters when null is rejected truthfully
what is P value and what used for
probability that effect as large as one seen in study could be from chance alone

used to determine conclusion of study
how do sample size and P value relate?
inverse relationship

sample up, P down
normal P is...
to determine if findings significant what do we do once we have P value?
use appropriate stat anal method

compare calc value to table value at specified P value

IF calc value significant
what 4 tools are used to measure effects of interventions on outcomes
relative risk reduction

absolute risk reduction

number needed to treat

number neede to harm
relative risk reduction
extent to which exposure reduces a risk in comparison to unexposed

proportion of risk in untreated group...

RRR= (Ru - Re) / Ru

or 1- RR
absolute risk reduction
simple...absolute value difference event rate of exposed and unexposed groups

ARR = Re - Ru
from what i understand these Re or Ru are cumulative incidence things
descriptive statistics vs inferential stats
D- methods and procedures for summarizing and describing data

I- methods used to make statements about the populations based on sample
attribute is
specific value of variable

ex female for gender
requirements of variables..

mutually exclusive
Types of variable are




Discrete vs continous
Dependant vs independant
What types of relationships can we have tween variables and what do they look like



Curvilinear - ex age vs intelligence
True score theory
takes into account the two components involved in measurement

Observed score = true ability + random error
random vs systematic error
random- from factors that randomly effect measurement
-not consistent effects
-add variability w/o changing average
-called noise

-affect measurement across sample
-positive or negative consistently
-called bias
reliability vs validity
R- repeatability or consistency

V- best availible approximation of the truth
Types of validity



External validity
can we generalize this to other persons, places, times

get a random large sample to get this
construct validity
are you using the correct instruments to measure what we are attempting to understand

are we executing this correctly design wise
internal validity
do we see cause and effect

is this the true cause or its it something else thats causing it
conclusion validity
to the results and findings match the conclusion given

are we reading the data correctly and taking it into account
3 major characteristics of a variable

central tendency


how to measure it
spread of values around the central tendency

range and standard deviation

will show how certain scores relate to the mean of sample
Statistical inference allows
decision making information about hypotheisiszed values of an unknown parameter
what kind of error is avoided and which can u not really help...
systematic error avoided since it can be eliminated

random error just kinda happens
point estimates provide information on random error T/F
F they do not...
Confidence intervals
interval estimation associating a measure statistical variation with a point estimate

has two numerical values defining range of values covering parameter being estimated
confidence interval better definition
range of values around point estimate tween upper and lower limits
how are precision and random error related

smaller random error more precise point estimate
look at notes pages 34- 37 cuz i dont know wtf is going on there...
do it
how do we see relationships tween indepenant variables, control variables and dependant variables
regression modelling!
Continous outcome

what kind of regression sued

what association measure we get
linear regression

regression coefficient
categorical (dichotomus)

what kind

associateion measure

odds ratio
time to event.....
cox regression

hazard ratio....
(thats not what i heard in drug lit....)
What are third variable effects?

what are 3 types
when other IV effect our results

changes relationship related to both

different interpretations when ignored or included
accounts for all or part of relationship

IV causes interveneing variable in turn causes DV

differs conceptually from mediation- confounder is not intermediate in causal sequence
alters strength or direction of relationship

relationship is diff at diff lvls of moderator
Medical utilization patterns

effectiveness of therapy depends on
therapy appropriate

medication used as recommended
suboptimal medication ultilization is
the point below which desired effect is unlikely to be achieved
extent behavoir coincides medical advice
patients failure consume medication according to directions
agreement tween pt and HCP regarding ultilization behavior
ISPOR does what...
defines medical compliance conformity to recommendation dosing, timing, freq
length of time taking medication in time...
What kinds of complaince are there
initial noncompliance

partial complinace


how can we measure complaince
direct measures- directly observed therapy

indirect measures- self report, provider esimates
contemporary emphasis on rights of ppl take risks to save themselves
sumthing about IRBs and other ethical issues...
dont care