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Statistics for Psychology Chapter 4
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Terms in this set (26)
theory
refers to a set of principles that attempt to explain one or more facts, relationships, or events
What's the difference between a theory and a hypothesis?
A hypothesis is a specific prediction that is often derived from a theory
hypothesis testing
a procedure for deciding whether the outcome of a study of the individuals in a sample supports a particular theory or practical innovation (which is thought to apply to a population)
Pyschologists conduct research to test whether the results of a research study, which examines a ______, support a hypothesis, which applies to a _________
sample... population
in virtually any type of psychological research, the researcher determines the probability of obtaining a particular result if
the opposite of what she predicting is true
population 1 refers to
the individuals who receive the experimental treatment
population 2 refers to
the cases who do not receive the experimental treatment and a kind of a comparison baseline of what is already known
research hypothesis
a prediction that a treatment of some kind has an effect on behavoir
alternative hypotheis
another name for the research hypothesis
the null hypothesis claims
the opposite of what the researcher predicts
which population (of 1 and 2) do we know about?
population 2
under what conditions are population 1 and population 2 the same?
when the null hypothesis is true
when the sample is the a single individual, what serves as the comparison distribution?
the distribution of scores that make up population 2
critical value/cut-off sample score
the minimum score that the sample score must exceed in order to reject the null hypothesis
conventional level of significance
levels of significance/alpha levels widely used in psychology (p < .05, p <.01)
with a .05 significance level, a statistically significant result
has a probability of occurrence that is less than 5 percent, if the null hypothesis is true and is so extreme that it results in the rejection of the null hypothesis
directional hypothesis
research hypothesis predicting a particular direction of difference between populations- for example, a prediction that one population has a higher mean than another population
statistically significant
conclusion that the results of a study would be unlikely if i n fact the sample studied represents a population that is no different from the population in general; an outcome of hypothesis testing in which the null hypothesis is rejected
comparison distribution
distribution used in hypothesis testing that represents the population situation if the null hypothesis is true. it is the distribution to which you compare the score based on your sample's results. it is made up of the same kinds of numbers as those of the sample's results
null hypothesis
statement about a relation between populations that is the opposite of the research hypothesis' statement that in the population there is no difference (or the opposite to that predicted) between populations; contrived statement set up to examine whether it can be rejected as part of hypothesis testing
one-tailed test is used for a
directional hypothesis
nondirectional hypothesis
predicts a difference but does not specify the direction of the predicted difference (two-tailed test)
what is the biggest complaint about significance tests?
they are so often and badly misused
distribution of means
comparison distribution when a hypothesis test is based on a sample of more than one individual
sampling distribution of the mean
another name for the distribution of means
the characteristics of the population of individual scores and the number of scores in each sample
are needed to directly determine the characteristics of a distribution of means
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