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Flashcards in Scientific Investigation Deck (33):

What are the 5 steps of scientific investigation?

Per Kazdin (2003):
Formulate a testable hypothesis
Select a research method and design the study
Collect the data
Analyze the data
Report the findings


What is a hypothesis?

A tentative statement about the relationship between variables


What is the null hypothesis?

The hypothesis that specifies that there is no difference between conditions or groups in the experiment on the dependent measures of interest


What is the alternate hypothesis?

The hypothesis that specifies that there is a difference between conditions or groups in the experiment on the dependent measures of interest


What is the independent variable (IV)?

The variable (construct, experimental manipulation, intervention, factor) that is manipulated in the study


What is the dependent variable (DV)?

The measure designed to reflect the impact of the IV, experimental manipulation, or intervention


What is a true experiment?
(Kazdin, 2003)

Must meet the following conditions:
Random assignment of participants
Maximum control of IVs/condition of interest
Can include alternate conditions (treatment, control)
Can control possible sources of bias within the experiment that permit the comparison of interest


What is a quasi-experimental design?
Per Kazdin, 2003

Conditions of the experiment are approximated
Restrictions are placed on some aspect of the design


What is statistical significance?

Per Kazdin (2003)
Criterion used to evaluate the extent to which the results of a study (differences between groups or changes within groups) are likely to be due to genuine rather than chance effects


How is statistical significance indicated?

Called alpha
Norms for different fields exist - .05 typically used for educational/psychological research
This is the level of risk associated with rejecting the null hypothesis


What is a Type I error?

Rejecting a true null hypothesis
concluding there is a significant difference when really there isn't


What is statistical power?

Per Kazdin (2003)
The probability of rejecting the null hypothesis (that there are no differences) when in fact the hypothesis is false
AKA: detecting a difference between groups when there is truly a difference
AKA: the extent to which an investigator can detect a difference when one exists


What is power analysis?
(Kazdin, 2003)

A way of deriving at the ideal sample size number
Increase power by increasing the sample size


What are the 4 concepts involved in increasing power?
(Kazdin, 2003)

Statistical significance - typically .05
Effect size - measures the strength of the relationships
Power - typically .8
Sample Size - calculated based on the other three (# of participants per # of groups)
**Know 3 to determine the 4th**


What are the common factors of effect size?

Cohen (1998): .2 for small, .5 for medium, .8 for large
Common metrics include Cohen's d, Pearson's r, and eta-squared


What are the types of data than can be included in research?
(Ruderstram and Newton, 1992)

Physiological data
Psychological report
Archival data
Direct observation


What is Type II error?

failing to reject the null hypothesis when it is actually false
concluding there isn't a statistically significant difference when there really is one that you didn't find


What is an effect size?

the relationship or association or difference that you have set out to investigate


What is the correlation coefficients?

used to analyze the relationship between two variables
the size of the relationship between two variables on a standard scale (0-1)


What is an effectiveness study?

applies to actual patients, the actual population


What is an efficacy study?

applies to RCT, random sampling from the population, discreet TX


What is between groups?

looking at differences between different groups


What is within groups?

looking at differences within
looking at the same person over time


What is a main effect?

the overall effect of one independent variable


What is the interaction effect?

only found in factorial designs in which the 2+ IVs are crossed
occurs whenever the effect of one IV depends on the level of te other


What is a moderator?

variable that influences the strength of a relationship between two other variables


What is a mediator?

variable that explains the relationships between two other variables


What is a confounding variable?

variable that is influencing both the DV and IV and is not accounted for


What is the citation for scientific investigation?

Kazdin, 2003


What is the citation for the types of data used in scientific investigation?

Ruderstram and Newton, 1992


What is indicated by predictor?



What is indicated by relationship?



What is indicated by adjusting?