QUESTIONS WITH ANSWERS GRADED A+
◉ Experimental condition/group. Answer: involves exposing
participants to a treatment or an "active" level of the IV.
◉ Control condition/group. Answer: participants do not receive the
treatment of interest or are exposed to a baseline level of an IV
◉ Type of between-subject design (independent groups-design).
Answer: participants are randomly assigned to the various
conditions of the experiment
◉ Block randomization. Answer: we conduct a single round of all the
conditions, then another round, then another, for as many rounds as
needed to complete the experiment. Within each round, the order of
conditions is randomly determined.
◉ matching variable. Answer: a characteristic on which we match
sets of individuals as closely as possible.
◉ matched-groups design. Answer: each set of participants that has
been matched on one or more attributes is randomly assigned the
various conditions of the experiment.
,◉ subject variable. Answer: a personal characteristic on which
individuals vary from one another.
◉ Natural-groups design. Answer: a researcher measures a subject
variable, forms different groups based on people's level of that
variable, and then measures how the different groups respond on
other variables.
◉ Is a Natural-groups design an experiment?. Answer: First, if a
subject variable is the sole basis for creating different groups or
conditions in a study, should we consider that subject variable to be
an "independent variable"?
Second, and more important issue is whether a single-factor natural-
groups design constitutes an experiment
◉ Random assignment v. random sampling. Answer: Random
sampling: is a procedure in which each member of a population has
an equal probability of being selected into a sample chosen to
participate in a study.
- The goal of random sampling is to select a sample of people whose
characteristics are representative of the broader population from
which those people have been drawn.
, - Random assignment: of participants, within the context of
experiments, is used to determine the specific condition to which
each participant will be exposed
- Goal of random assignment in experiments is to take whatever
sample of people you happen to put together and place them in
different conditions in an unbiased way so that, at the start of the
study, the researcher may assume that the groups of participants in
the various conditions are equivalent, overall, to one another.
◉ Advantages of within-subjects design. Answer: 1) that they need
fewer participants to obtain the same amount of data per condition
than do between-subjects designs.
2) rather than recruiting a small number of participants to obtain
the same amount of data per condition as a between subjects design,
we can instead recruit the same number of participants and thus
collect more data per condition
3) the only approach that can be used to answer certain types of
questions.
4) Finally, compared to between-subjects designs, within-subjects
designs do a better job of creating equivalent groups at the outset of
the experiment. Nothing can be more equivalent than having the
same participants in all the conditions!!