Introduction to Behavioral Research Methods Ch. 10

One way designs

experimental designs in which only one independent variable is manipulated

Two group experimental design

there are only two levels of the independent variable (and thus, two conditions)

Posttest-only design

the dependent variable is measured only after the experimental manipulation has occurred

Pretest posttest designs

researchers measure the dependent variable twice - once before the independent variable is manipulated and again afterward

Pretest sensitization

administering a pretest may sensitize participants to respond to the independent variable differently than they would respond if they are not pretested

Factorial design

an experimental design in which two or more independent variables are manipulated

Factor

an independent variable

Randomized groups factorial designs (completely randomized factorial design)

participants are assigned randomly to one of the possible combinations of the independent variables

Matched-subjects factorial design

involves first matching participants into blocks on the basis of some variable that correlates with the dependent variable. There will be as many participants in each matched block as there are experimental conditions. Then the participants in each block are randomly assigned to one of the n experimental conditions.

Repeated measures (or within subjects) factorial design

requires participants to participate in every experimental condition.

Mixed factorial design / between within design / split plot factorial design

a design that combines one or more between-subjects variables with one or more within-subjects variables

main effect

the effect of a single independent variable in a factorial design (ignoring the effects of the others)

interactions

the combined effect of two or more independent variables such that the of one independent variable differs across the levels of the other independent variables

Participant variables (subject variables)

a personal characteristic of research participants, such as age, gender, self-esteem, or extraversion

Expericorr (expericorr/mixed) factorial designs

combine features of an experimental design in which independent variables are manipulated and features of correlational designs in which participant variables are measured.

Median-split procedure

the researcher identifies the median of the distribution of participants' scores on the variable of interest, and then classifies participants with scores below the median as low on the variable and those with scores above as high.

Extreme groups procedure

the researcher pretests a large number of potential participants, then selects participants for the experiment whose scores are unusually low or high on the variable of interest

Moderator variable

a variable that qualifies or moderates the effects of another variable on behavior