A threat to the internal validity of the study resulting from pre-existing differences between groups under the study; the differences affect the dependent variable in was extraneous to the effect of the independent variable
What is selection threat.
100
Subjects score differently on the post-test because of a combination of the pre-test and the intervention
What is testing-intervention interaction.
100
The assignment of subjects to treatment conditions in a random manner.
What is randomization
100
Study in which the researcher collects data without introducing an intervention
What is non-experimental research or observational research
100
A variable that can have only one of two values, such as yes/no or male/female.
What is a dichotomous or categorical variable
200
The occurrence of events external to an intervention, but concurrent with it, that can affect the dependent variable and threaten the study's internal validity.
What is history threat.
200
Because the sample is not representative of the population, the intervention is effective only in the study sample.
What is selection-treatment interaction.
200
An experimental design in which one group of subjects is exposed to more tan one condition or treatment, preferably in random order.
What is crossover design
200
An error created by accepting the null hypothesis when it is false (i.e. the researcher concludes the no relationship exists when in fact it does)
What is a Type II Error
200
A categorical variable whose values have a logical order.
What is an ordinal variable
300
A threat to the internal validity of a study that results when changes to the outcome measure (dependent variable) result from the passage time.
What is maturation threat.
300
A pre-test arguments the effect of an experimental treatment only in some groups.
What is selection-testing interaction.
300
The division of a sample of a population into smaller units (e.g. males and females), typically to enhance representativeness or to explore results for subgroups of people
What is stratification
300
A design for an intervention study in which subjects are not randomly assigned to treatment conditions
What is a quasi-experimental design
300
A measurement that, in theory, can have an infinite number of possible values.
What is continuous or discrete*
400
The loss of participants over the course of a stud, which can create bias by changing the composition of the sample initially drawn.
What is attrition threat.
400
The effect of the intervention is modified by subjects' reactions t the study tests, measures, or setting.
What is reactive arrangements.
400
The pairing of subjects in one group with those in another group based on their similarity on one or more dimension, to enhance the overall comparability of groups.
What is matching
400
An error created by rejecting the null hypothesis when it is true (i.e. the researcher concludes that a relationship exists when in fact it does not)
What is a Type I Error
400
A categorical variable for which there is no logical order (ex. religious affiliation).
What is a nominal variable
500
The effect of having scores at or neat the lowest possible value, which can constrain the amount of downward change possible and all tends to to reduce variability in a variable.
What is the floor effect.
500
Many subjects in a study drop out of one of the groups, and fewer drop out of the other group.
What is high differential attrition rate.
500
The use of statistical procedures to control confounding influences on the dependent variable.
What is statistical control?
500
A study in which researchers actively introduce an intervention or treatment