Psy 251 ch 4

statistically significant

conclusion that the results of a study would be unlikely if in 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. It represents the populations situation if the null hypothesis is true. It is the distribution to which you compare the score based on you sample's results.

two-tailed test

hypothesis testing for a non-directional hypothesis; the situation in which the region of the comparison distribution in which the null hypothesis would be rejected is decided between the two sides (tails) of the distribution.

one-tailed test

hypothesis-testing procedure for a directional hypothesis; situation in which the region of the comparison distribution in which the null hypothesis would be rejected is all on one side (tail) of the distribtuion

conventional levels of significance (p < 0.5 < 0.1)

levels of significance widely used in psychology

cutoff sample score

point in hypothesis testing, on the comparison distribution at which, if reached or exceeded by the sample score, you reject the null hypothesis. Also called the critical value.

hypothesis

prediction, often based on internal observation, previous research, or theory, that is tested in a research study

hypothesis testing

procedure for deciding whether the outcome of a study supports a particular theory or practical innovation

directional hypothesis

research hypothesis predicting a particular direction of difference between populations - for example, a prediction that the population like the sample studied has a higher mean than the population in general

nondirectional hypothesis

research hypothesis that does not predict a particular direction of difference between the population like the sample studied and the population in general

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 a difference opposite to that predicted) between populations; contrived statement set up to examine whether it can be rejected as part of hypothesis testing

research hypothesis

statement in hypothesis testing about the predicted relation between populations (often a prediction of a difference between population means)

theory

a set of principles that attempt to explain an important psychological process