Internal/External validity

Question 1

dependent variable

Answer 1

measures to determine the effects of the indep variable

Question 2

independent variable

Answer 2

manipulated or controlled by the researcher

Question 3

internal validity

Answer 3

assured when the changes in the dep variable result only from the controlled, manipulation of the indep variables

Question 4

external validity

Answer 4

assured when the researcher can generalize results from a sample to the population of interest

Question 5

threats to internal validity

Answer 5

history- uncontrolled events between pre and post tests

maturation- effects related to time rather than to the events occuring

attrition-loss of subjects

testing- more exposure to evaluation tools

instrumentation- calibration. Needs to be accurate.

statistical regression- selection based on extreme high or low test scores.

selection effects/bias

placebo effect- subjects expectations about the benefit

Question 6

threats to external validity

Answer 6

sample to population effect-concerns the extent to which the researcher can generalize the results of a study to the defined population. Does study really represent the population?

description of the experimental treatment- author must describe the experimental treatment for replication

exposure of multitreatments

hawthorne effect- subjects change behavior because they know they’re watched

researcher effect- subjects act differently to the particular operator administering the experimental procedure

pretest effects- can cause different results