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112 Cards in this Set

  • Front
  • Back
Empirical Research
Uses inductive reasoning to obtain evidence from particular cases and make inferences about general principles (bottom up approach); knowledge gained via systematic observations; inductive reasoning-obtain evidence from particular cases and make inferences about general principles.
Experimental Research
Characterized by control, manipulation, and randomization; involves the application of some form of intervention or treatment; able to infer cause and effect
Descriptive Research
Characterized by observation without manipulation or control; experiments of nature; observational studies comparing groups or conditions; UNABLE to infer cause and effect.
Qualitative research
inductive reasoning, purposeful (small) sample, emerging meaning/hypothesis; new topic/closed culture; rich in depth analysis; close E/P interaction; awareness of bias; interpretive themes; interactive; clinical utility
Quantitative Research
deductive reasoning, large (random) sample; testing hypothesis; uses instruments; a quick snapshot; E/P distance objectivity; try to control bias; use of statistics; group (sample) data; generalization
Dependent Variable
answers the question: what do I observe?; what you measure in an experiment and what is affected in the experiment; what can change or is dependent based on the independent variables.
Independent Variables
stands alone; isn't changed by other variables (ex: age)
Null Hypothesis
statistical statement indicating no difference between two (or more) groups.
Measure of effect size
refers to the magnitude of a difference between scores expressed as a standard score. (ex. a range of 0-3 large effect size is .8; moderate is .5; small is .2)
Population Parameter
all members of a defined population
P<.05
statistically significant; the most liberal level most likely to reject the null hypothesis
ANOVA
analysis of variance; allowing for testing across 3 or more groups; avoids problems of multiple T tests; (a) one way anova- ex three levels of therapy (b) two way anova- ex grade x gender (3x2); formula: F=variance b/w (treatment + error)/ variance within (error)
Four levels of data
Nominal- categorical
Ordinal- Categorical and rank
Interval- equal intervals/arbitrary zero
Ratio- established true zero
Statistical Significance
likelihood or probability; not happening by chance
Statistical Power
the probability of correctly rejecting the Null Hypothesis (influenced by N)
Non-directional experimental hypothesis:
there is a difference but there is not enough information to speculate on the direction of the differences
Directional experimental hypothesis
states that one particular group's average is higher than the other group's average.
Confidence interval
account for sampling error when generalizing to the population parameter by increasing the likelihood of including the parameter; typically set at 95% (willing to be wrong 5% OTT) and 99% (willing to be wrong 1% OTT) when data are considered to be normally distributed
Type I and Type II Error
Type I- incorrectly rejecting the Null hypothesis (alpha error)

Type II: failing to reject a false Null Hypothesis (beta error)
Negatively skewed distribution
the median is higher than the mean; skewed to the left
Positively Skewed distribution
the mean is higher than the median; skewed to the right
Normal, platykurtic, and leptokertic distributions
Normal: bell shaped curve; symmetrical, infinity at each tail, mean, median, mode at center.

Leptokurtic- peaked and fat tails (Kur +)

Platykurtic- less peaked and thinner tails (Kur -)
Standard error of the mean
standard deviation of the mean
Tabled Critical Values
Critical values on a t and z score are the values the calculated values must exceed to be statistically significant.
Cohen's D
Widely used measure of effect size; divide the difference in the means of the two groups by the SD of one of the groups (typically control group) or if the SD are not similar use the pooled standard deviation of the two groups.
A priori and post hoc testing
Priori: done when prior theory leads to a specific hypothesis about where significance differences might be found. Revised version of T test.
Post hoc: specific comparisons of groups testing with a variety of multiple comparison tests. Analyzes all possible comparisons.
Sampling Error
random error (created by random selection)
Multivariant Experiment
MANOVA: examines the effects of one or more independent variables on multiple dependent variables. Helps control overall type I error.
Parametric Experiment
interval and ratio data, homogeneity of groups, used for comparing variance
Norm referenced test
compares an individual's performance with that of a norm group
Content of major sections of a manuscript
1. Title: key independent/dependent variables
2. Authorship
3. Abstract: key results; concise and efficient
4. Literature review: Justification and logic for study; research question
5. Methods: participants; procedure; research design
6. Results: brief statement of questions and general findings. Then detailed graphs and results. No interpretations just facts
7. discussion: interpret resultsonly if significant, suggestions for future studies
8. acknowledgement
9. References:
10. Appendices: explain procedures, selection criteria, measurements, algorithms, tests, etc.
The peer review process
1.
2.
3.
4.
Publication lag
2-3 years
Z and T tests
1. z scores: provide precise indications of the area under the curve from the mean of zero to points on the baseline that define (in both +/- directions) the total area under the curve.
2. T tests- small sample sizes and the shape of distribution varies with the number of scores/participants. values increase with smaller samples b/c of greater variability.
Measures of central tendency and dispersion
standard deviation, variance, range
Sagan suggests that science involves a balance between what two concepts?
Research/asking any question and defending idea (expert criticism)
Siegel suggests that it's not enough to demonstrate that a therapy protocol works but that we also need to:
explain how it fits into the overall model and how it will benefit client.
Clinical Significance has to do with:
how the client feels (asking the client their opinion) a functional issue; meaningful or clinical change; clinical utility and effect size.
Statistical significance has to do with:
probability
In Michael Chial's example of the competitors in the 100 M foot race, what are the examples of:
Nominal data:
Ordinal data:
Interval Data:
Nominal: categories (gender, race, etc).
Ordinal: category and rank (order of finish)
Interval: precise measurement of the time difference b/w individuals (arbitrary zero)
List the characteristics of interval-level data
arbitrary zero; mutually exclusive categories; can be used with parametric statistics; equal occurring intervals/quantities; rank, order, differences
The best indicator of central tendency for ordinal data scores is ______. This would be especially true when the data is _______.
Median
Skewed.
The two basic purposes of inferential statistics:
1. accept/reject null hypothesis
2. infer sample to a population
A class is titled statistics and not parameters because:
You cannot measure parameters because this is an entire population (greek symbol). You can only test a sample which would be a statistic (roman letter) that you then infer to a parameter.
To be worthwhile a theory must be:
concrete enough to be testable and specific
Typical measures of variability or dispersion are:
standard deviation; variation; range
When investigating a phenomenon that is not well understood the test approach would likely be a: quantitative or qualitative approach?
qualitative approach: you need to find out important variables and factors.
What are the purposes/advantages of using standard scores? What are some examples?
You are able to compare one score to a group of scores.
Example: z score, t test, effect size
What proportion of the total area under the normal curve is defined by:
-1 sd to +1 sd
-2 sd to +2 sd
-1/+1: 68%
-2/+2: 95%
What is the purpose of developing a confidence interval when making inferences from sample statistics to the population parameters? What are the two confidence intervals which are calculated?
It is a margin of error for estimating the mean of the population parameter. Intervals 95% and 99% confidence interval used often.
Why use z score of 1.96 to define the 95% confidence interval?
95% is roughly the area b/w -2/+2 sd from the mean and the 1.96 would be about the mean in a normal distribution.
Who developed the t-distribution and why were they created?
William Gosset in dublin Ireland at the Guiness brewery....created to measure deviations and variance in small sample populations.
How does the shape of the t-distribution differ from the normal distribution. Why does the shape of the t-distribution vary according to df?
The shape differs in that it is usually a flatter curve with tails slightly upward. With higher df the shape will resemble more of a normal curve b/c of more samples. With lower df it will become flatter b/c of wide range of scores w/few people.
The standard error of the mean is the standard deviation of:
mean scores
What is the purpose of the values in the t-tables?
Critical values: Sample data must be higher than critical values to be statistically significant.
Why do more scores cluster near the middle of a distribution when you increase the number of subjects?
The more scores you have the less variability between all the scores and the mean will be closer to the middle point btween them. More subjects= higher statistical significance
The central goal of inferential statistics in the behavioral sciences is to determine whether the observed ________between two groups is great enough to justify the conclusion that they are not due to _______ or variations among individuals.
differences; sampling error.
In the following sequence of the steps in hypothesis testing which critical step is missing?
-state the null hypothesis
-select a statistical test
-calculate the test statistic
-contrast the calculated value w/critical value
-draw conclusions
Most important is what you alpha level will be or probability level. Type I error.
Describe the Null Hypothesis:
The null hypothesis is the previously held idea about a relationship between two groups where there is no difference between the two.
Describe a directional research hypothesis
Proposing that one of the group's mean is higher than the other group's mean. One tailed test.
Explain critical (tabled) values and calculated values obtained from a statistic
The critical values are the value your calculated value needs to be greater than or equal to to be statistically significant. The calculated value is the df, whether it is a two tailed or one tailed test, and the alpha level.
Are the critical values for a t-statistic greater for a one-tailed or two-tailed test?
They are greater for a one-tailed test because instead of the 5% not accounted for (Type I error) and placing it on one end rather than splitting it makes the statistic greater. All alpha in one tail so critical value is closer to the mean.
The standard error of the difference of Sx1-x2 is
Standard deviation of mean/different scores
The choice of an alpha level and a one or two-tailed statistical test should be guided by the: _____ but not by: ______
literature/research question you are

but not by: convenience
What are the basic steps in conducting research?
-become familiar with the literature
-recognize an issue, problem, formulate your question
-create a research strategy/design
-develop your rationale and methods
-gather your data (run participants)
-analyze your data (results)
-interpret and draw conclusions
-report the results to your peers
Serendipity
discovering something not originally sought
Pilot Studies
essential for understanding (saving time and money)
The principles of parsimony
do not make more assumptions than the minimum needed to explain something. Provide the simplest explanation using the fewest possible assumptions. Choose from a set of otherwise equivalent models of a given phenomenon, the simplest one.
Types of research
1. basic: search for understanding; how things work; often without concern for application; may have eventual or unintended application at some later time
2. applied- sometimes referred to as clinical research; goal is immediate application in a (clinical) setting
Types of research continued
1. Descriptive research: observation without manipulation or control; experiments of nature; observational studies comparing groups and conditions; UNABLE to infer cause and effect
2. experimental research: control, manipulate, and randomize; application of some form of intervention or treatment; able to infer cause and effect.
Rationalism
knowledge gained via logical thought; deductive reasoning-apply general principles to make inferences about specific cases.
Define Theory:
a theory is a set of interrelated constructs, concepts, definitions, and propositions that represents a systematic view of a phenomena by specifying relationships among the variables. The purpose is to explain and predict the phenomena.
What are the steps in publishing a manuscript?
-read information for authors
-send manuscript to journal editor
-associate editor sends to reviewers
-reviewers select 3-4 options
-associate editor makes recommendation to editor
-editor makes decision and corresponds with authors
-time lag to get published is 2-3 years
What are the four choices peer reviewers have?
1. accept it
2. revise with minor errors
3. revise with major errors
4. outright reject
When reviewing a manuscript what is the internal criteria for a reviewer?
information independent of the subject area; the technical aspect of the ms. regarding threats to internal and external validity of the study, organization, and clarity of writing.
External Criteria?
information related to the subject area; how does the research relate to the field; is it a meaningful and timely contribution (reviewer must have expertise in this area)
Define the technician
more likely to base decisions on dogmas, an authority. The focus is on the book or manual.
Professional:
knows many strategies and techniques; considers alternative explanations for behavior and outcomes. The focus is on the person and their goals.
What are the 4 basic strategies for diagnostic decision making?
1. Pattern recognition: recognition of visual and/or auditory features
2. multiple branching: flowchart sequencing through diagnostic steps; compensates for less experience but works poorly w/complex and dynamic problems
3. Diagnosis by exhaustion: search for all possible facts following extensive testing
4. Hypothetico-deductive: hypothesis generated based on experience, pattern recognition, and understanding nature of problem. Primary strategy is to disprove one or more working hypothesis.
Limitations of group design
lack homogeneity of participants; individual response to intervention; averaging of scores; ethical issues
What is a good measure of clinical significance?
Cohen's D
What is another name for non-parametric statistics?
distribution free statistics; no assumption of a normally distributed population.
Paragraph with Confidence interval
Although sample statistics provide a point estimate of teh population parameter (mean) there is always the possibility of sampling error. Therefore confidence intervals are determined based on the estimated standard error of measurement from the sample data. Confidence intervals based on the sample data increase the likelihood of including the parameter and are typically set at 95% (critical values of +/- 1.96) or 99% critical values of (+/- 2.58) when the data is considered to be normally distributed.
Meta-analysis
studies are the subjects, effect size (like standard scores, can compare data across areas)
Central limit theorem
1. Means of a multitude of equal-sized samples drawn from a normally distributed population are themselves normally distributed.
2. The means of a multitude of qual sized samples, regardless of the shape of the population distribution approaches a normal distribution as the sample size reaches 30.
3. the means of a multitude of normally distributed sample means is known as the population mean.
How are type I and type II errors related?
inversely. as one increases the other decreases.
What are the methods of analyzing relationships with parametric statistics?
Pearson Product moment correlation coefficient and multiple-regression analysis (must know nature of data)
What are the two limitations for t tests with 3+ levels of experience?
not efficient and using multiple t comparisons increases the likelihood that one or more of them will reach a significant difference by chance. Probability of falsely rejecting the null (a type 1 error) is increased.
ANOVA
ratio of systematic variance due to the treatment effect regarding the variance due to sampling (between-group) variance and measurement error (within-group). Determines the variability between groups is greater than within groups.
3 assumptions of ANOVA
independence among groups of subjects, sampling distribution of scores follow a normal curve, and variances of the scores in each group are equal (homogeneity of variance)
How can the assumption of homogeneity not be violated with ANOVA?
as long as each group is constituted by an equal number of subjects of scores.
Descriptive Statistics Goals
Goals: describing a sample of data (central tendency and dispersion); describing how a single datum relates to an entire sample (standard score); describing the amount and direction of association between two samples of data.
What do measures of dispersion describe?
dissimilarities in a group of data; the way events scatter. (range, variance, standard deviation, and standard error of the mean)
What is the standard error the mean considered "normalized?"
it takes sample size into account, therefore it allows direct comparison of the amount of dispersion associated with different sized samples.
Standard scores express the relation of a single score to:
central tendency and dispersion of a group of scores. (z score)
What does a z score tell you?
where a particular raw score is placed on a set of scores
what does a standard score of zeor indicated? Positive? Negative?
Zero:particular raw score equals the mean; positive: occurs when a particular score exceeds the mean; negative: when a particular score is less than the mean. Magnitude tells how far a raw score is from the mean (in units of SD)
Z scores are "standardized" how? And when are they valid?
they allow direct comparison of distributions having different means, ranges, and dispersions; they are valid only if based upon large distributions of interval or ration scale numbers for which the mean and median are similar
What do correlation coefficients describe?
degree of similarity between distributions
What are the commonly used correlation coefficients?
interval/ration- pearson product moment correlation coefficient; ordinal- spearman rank-order; nominal- contingency coefficient
What does a correlation of 0 indicated? Positive? Negative? (+1/-1)
zero means the two sets of data are unrelated. Positive indicates a direct relationship and negative indicates an inverse relationship.
What is the magnitude of correlation coefficient?
<.2 "negligible", .2-.4 weak, .4-.7 moderate, .7-.9 strong, .9-1 very strong
What does the square of the correlation coefficient (coefficient of determination) indicate?
strength of association between two sets of data expressed as a percentage of total variation in scores attributable to whatever the distributions have in common.
Hypothesis testing
two or more sets of sampled data can be compared to determine whether they differ with respect to some specific index or with respect to the entire distribution.
What is the central goal of inferential statistics?
determine whether observed differences between groups are great enough to justify the conclusion that they are real and not due simple to random errors of measurement, or variations among individuals.
Describe goal of inferential statistics
ascertain whether data drawn from two or more groups differ with respect to some specified characteristic such that differences may be considered "statistically significant."
Some inferential tests are designed to compare what?
on empirical group to a population already known; two empirical groups; comparison of 3 or more groups.
What do most inferential tests assume?
That groups to be compared to each other are statistically independent (subjects have been measured only once); this is b/c procedures involving repeated observations systematically constrain the variance of events.
Post hoc
Statistical tests of groups not independent of each other (test-retest measures)
What are most research hypotheses about?
measures of central tendency, dispersion, or entire distributions
YOu should select a test for your research hypotheses that conforms to what?
a. the scale of measurement implicit in data acquisition b. the nature of what the hypotheses are about c. the number of groups being compared d. whether the groups are statistically independent or related.
W/ research hypotheses selection of a statistical test specifies what?
statistical model, test statistic, and a sampling distribution for that test statistic.