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z test
parametric inferential statistical test of the null hypothesis for a single sample wehre the population variance is known.

sampling distribution
distribution of sample means based on random samples of a fixed size from a population.

standard error of the mean
standard deviation of the sampling distribution

central limit theorem
states that ofr any population with a mean µ and a standard deviation σ, the distribution of sample means for sample size N will have a mean of µ, a standard deviation of σ/√N, and will approach a normal distribution as N approaches infinity.

critical value
value of a test statistic that marks the edge of the region of rejection in a sampling distribution, where values equal to it or beyond it fall in the region of rejection.

region of rejection
are of a sampling distribution that lies beyond the test statistic's critical value; when a score falls within this region, H_{0 }is rejected.

statistical power
probability of correctly rejecting a false H_{0}.

confidence interval
an interval of a certain width that we feel confident will contain µ.

t test
a parametric inferential statistical test of the null hypothesis for a single sample where the population variance is not known.

student's t distribution
a set of distributions that, although symmetrical and bellshaped, are not normally distributed.

degrees of freedom (df)
the number of scores in a sample that are free to vary.

estimated standard error of the mean
an estimate of the standard deviation of the sampling distribution.

chisquare (x^{2}) goodnessoffit test
nonparametric inferential procedure that determines how well an observed frequency distribution fits an expected distribution.

observed frequency
the frequency with which participants fall into a category.

expected frequency
the frequency expected in a category if the sample data represent the population.

a __ is a distribution of sample means based on rndom samples of a fixed size from a population
sampling distribution

the __ is the standard deviation of the sampling distribution.
standard error of the mean

the set of distributions that, although symmetrical and bellshaped, are not normally distributed is called the ___.
student's t distribution

the ___ is a parametric statistical test of the null hypothesis for a single sample where the population variance is not known.
t test

___ and ___ frequencies are used in the calculation of the x^{2} statistic.
observed; expected

inferential statistics allow us to infer something about the __ based on the ___.
population; sample

the sampling distribution is a distribution of:
sample means

a onetailed z test is to ____ and a twotailed z test is to ___.
±1.645; ±1.96

which of the following is an assumption of the t test?
the sample size is typically less than 30.

parametric is to nonparametric as ____ is to ____.
t test; x^{2} test

which of the following is an assumption of x^{2} tests?
the sample should be randomly selected.

betweensubjects design
an experiment in which different subjects are assigned to each group.

posttestonly control group design
an experimental design in which the dependent variable is measured after the manipulation of the independent variable.

pretest/posttest control group design
an experimental design in which the dependent variable is measured both before and after manipulation of the independent variable.

confound
an uncontrolled extraneous variable or flaw in an experiment.

internal validity
the extent to which the results of an experiment can be attributed to the manipulation of the indpendent variable rather than to some confounding variable.

history effect
a threat to internal validity in whch an outside event that is not a part of the manipulation of the experiment could be responsible for the results.

maturation effect
a threat to internal validity in which naturally ourring changes within the subjects could be responsible for the observed results.

testing effect
threat to internal validity in which repeated testing leads to better or worse scores.

regression to the mean
a threat to internal validity in which extreme scores, upon retesting, tend to be less extreme, moving toward the mean.

instrumentation effect
a threat to internal validity in which changes in the dependent variable may be due to changes in the measuring device.

mortality (attrition)
threat to internal validity in which differential dropout rates may be observed in the experimental and control groups, leading to inequality between the groups.

diffusion of treatment
When a treatment given in a study group is shared with members of a control group.

experimenter effects
 the results of the study are biased by the experimenter's expectations.
 influence of the experimenter's behavior, personality traits, or expectancies on the results of his or her own research.

singleblind experiment
experimental procedure in which either the subjects or the experimenters are blind to the manipulation being made.

doubleblind experiment
experimental procedure in which neither the experimenter nor the subject knows the condition to which each subject has been assigned; both parties are blind to the manipulation.

subject effect
changes in the behaviors or responses of the participants may be due to information received from others participating in the experiment.

placebo group
group of subjects who believe they are receiving treatment but in reality are not.

placebo
simulated or otherwise medically ineffectual treatment for a disease or other medical condition intended to deceive the recipient.

floor effect
limitation of the measuring instrument that decreases its capability todifferentiate between scores at the bottom of the scale.

ceiling effect
limitation of the measuring instrument that decreases its capability todifferentiate between scores at the top of the scale.

external validity
the extent to which the results of an experiment can be generalized.

college sophomore problem
an external validity problem that results from using mainy college sophomores as subjects in research studies.

exact replication
repeating a study using teh same means of manipulating and measuring the variables as in the original study.

conceptual replication
study based on another study that uses different methods, a different manipulation, or a different measure.

systematic replication
study that varies from an original study in one systematic wayfor example, by using a different number or type of subjects, a different setting, or more levels of the independent variable.

correlatedgroups design
an experimental design in which the subjects in the experimental and control groups are related in some way.

withinsubjects design
type of correlatedgroups design in which the same subjects are used in each condition.

order effects
problem for withinsubjects designs in which the ordre ofthe conditions has an effect on teh dependent variable.

counterbalancing
mechanism for controlling order effects either by including all orders of treatment presentation or by randomly determining the order for each subject.

latin square
counterbalancing technique to control for order effects without using all possible orders.

matchedsubjects design
a type of correlatedgroups design in which subjects are matched between conditions on variable(s) that the researcher believes is (are) relevant to the study.

experiment in which different subjects are assigned to each group is a ___.
betweensubjects design

when we use ___, we randomly determine who serves in each group in an experiment.
random assignment

when the dependent variable is measured both before and after manipulation of the independent variable, we are using a ___ design.
pretestposttest control group design

___ is the extent to which the results of an experiment can be attributed to the manipulation of the independent variable, rather than to some confounding variable.
internal validity

a(n) ___ is a threat to internal validity where the possibility of naturally occurrng changes within the subjects is responsible for the observed results.
maturation effect

if there is a problem with the measuring device, then there may be a(n) ___ effect.
instrumentation

if subjects talk to each other about an experiment, then there may be ____.
diffusion of treatment

when neither the experimenter nor the subjects know the condition to which each subject has been assigned, a ___ experiment is being used.
doubleblind

when the measuring device is limited in such a way that scores at the top of the scale cannot be differentiated, there is a ___ effect.
ceiling

the extent to which the results of an experiment can be generalized is called ___.
external validity

when a study is based on another study but uses different methods, a different manipulation, or a different measure, we are conducting a ___ replication.
conceptual

if the order of conditions affects the results in a withinsubjects design, there are ____.
order effects

manipulate is to measure as __ is to ___.
independent variable; dependent variable

in an experimental study of the effects of stress on appetite, stress is the:
independent variable

in an exprimental study of the effects of stress on appetite, subjects are randomly assigned to either the nostress group or the stress group. these groups represent the __ and the __, respectively.
control group; experimental group

withinsubjects design is to betweensubjects design as __ is to ___.
using the same subjects in each group; using different subjects in each group.

the extent to which the results of an experiment can be attributed to the manipulation of the independent variable, rather than to some confounding variable refers to:
internal validity

Joann conducted an experiment to test the effectiveness of an antianxiety program. the experiment took place over a 1month time period. subjects in the control group and the experimental group (those who participated in the antianxiety program) recorded their anxiety levels several times each day. Joann was unaware that midterm exams also happened to take place during the 1month time period of ther experiment Joann's experiment is now confounded by:
history effect

Joe scored very low on the SAT the first time he took it. based on the confound of __, if Joe were to retake the SAT, his score should __.
regression to the mean; increase

when the confound of mortality occurs:
subjects are lost differentially from the experimental and control groups.

controlling subject effects is to controlling both subject and experimenter effects as __ is to __.
singleblind experiment; doubleblind experiment.

if you wer to use a bathroom scale to weigh mice in a experimental setting, your experiment would most likely suffer from a:
floor effect.

if we were to conduct a replication in which weincreased the number of levels of the independent variable, we would be using a(n) ___ replication.
systematic

most psychology experiments suffer from the __ problem because of the type of subjects used.
college sophomore problem

