Scientific Investigation Flashcards
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
Interview 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?
Regression
What is indicated by relationship?
Correlation
What is indicated by adjusting?
Covariates
