research methods ch 10 Flashcards
dependent variable/outcome variable
how a participant asks
how many dependent variables can an experiment have
at least two, could be more
how are the variables shown on a scatterplot
the independent variable is almost always not eh x-axis, dependent on the y-axis
control variable
any variable that the experiment holds constant on purpose, not really variables don’t vary
three rules of causal claims
covariance, temporal precedence, internal validity
comparison group/comparison condition
only an experiment can provide, no in our personal experiences
control group
level of an independent variable that is intended to represent “no treatment” or the natural condition
placebo group/placebo control group
when the control group is exposed to an inert treatment such as a sugar pill
confounds
possible alternative explanations, potential threats to internal validity
design confounds
an experimenter’s mistake in designing the independent variable
unsystematic variable
if it’s across both groups, not a confound
selection effect
in an experiment, when the kinds of participants in one level of the independent variable are systematically different from those in the other + when participants can choose their own groups
random assignment - simulation
up to 98% of the time it creates similar groups with as little as 4 participants
matched groups/matching
first measure participants on a particular variable, match up participants in pairs, within that set randomly assign each one to conditions
independent-groups design
separate groups of participants are place into different levels
within-groups design
each person is presented with all levels of the independent variable
posttest-only design
participants are randomly assigned to independent variable groups and are tested not eh dependent variable once
pretest/posttest design
participants are randomly assigned to at least two groups and are tested on the key dependent variable twice, once before and once after exposure to the independent variable
when is pretest/posttest used
for improvement over time + when researchers want to make sure random assignment made groups equal
types of within-groups design
repeated-measures design, concurrent-measures design
repeated-measures design
participants are measured on a dependent variable more than once, after exposure to each level of the independent variable
concurrent-measures design
participants are exposed to all the levels of an independent variable at roughly the same time, and a single attitudinal or behavior preference is the dependent variable
order effects
being exposed to one condition first changes how participants react to the later conditions
types of order effect
practice effects/fatigue effects and carryover effect
practice effects/fatigue effects
long sequence might lead participants to get better at the task or to get tired or bored toward the end
carryover effect
some of the contamination carries over from one condition to the other
counterbalancing
presenting the levels of the independent variable to participants in different sequences
how to fix order effects
counterbalancing
types of counter balancing
full counterbalancing, partial counterbalancing, Latin square
full counterbalancing
all possbile condition orders in a randomized order for every subject
partial counterbalancing
only some of the possible condition orders are represented, present the condition in a randomized order for every subject
Latin square
formal system to ensure that every condition appears in each position at least once
three disadvantages for within-subject design
potential for order effects (no internal validity), might not be possible or practical (learning how to ride a bike), when people see all levels of the independent variable they can change how they normally act
demand characteristic/experimental demand
a cue that can lead participants to guess the experiment’s hypothesis
manipulation check
extra dependent variable that researchers can insert into an experiment to convince them that their experimental manipulation worked
when is manipulation check most oftenly used
when the intention is to make participants think or feel a certain way
pilot study
a simple study, using a separate group of participants that is completed before (or after) the study of primary interest to confirm the effectiveness of the manipulation
how can effect size be expressed
in original units or r, also in d (standardized effect size, takes into account both the difference between means and the spread of scores within each group - when d is large, the independent variable caused a large change)
when are original units useful
when you want to estimate the real-world impact
when is d useful
when you want to compare the results found in one study to a body of knowledge