psyc 60 steiner chps 16-19

a statistical technique for testing differences in the means of several groups

an analysis of variance wherein the groups are defined on only one independent variable

1. populations are normally distributed

2. populations have homogenous variances

3. the individual observations are independent from one another, ie, one person's score doesn't influence another person's score

the hypothesis that all population mean are equal

the sum of squared deviations around some point (usually around a mean or predicted value)

variability among group means

variability among subjects in the same treatment group

mean square; SS/df

the ratio of MS_group to MS_error, or MS_between to MS_within

eta squared; SS_group/SS_total

omega squared

techniques for making comparisons between 2 or more group means subsequent to an analysis of variance

the probability that a family of comparisons contains at least one type 1 error

• we want to keep this down

1. Protected t (fisher's least significant difference (LSD))

2. Bonferroni correction

3. Tukey procedure

a technique in which we run t tests between pairs of means only if the analysis of variance was significant

a multiple comparison procedure in which the family-wise error rate is divided by the number of comparisons

• divide α by the number of comparisons you want to make

a multiple comparison procedure for making pairwise comparisons among means while holding the familywise error rate at α

another word for IVs in the ANOVA

an experimental design in which every level of one variable is paired with each level of one variable

an experimental design involving two IVs in which every level of one variable is paired with each level of one variable

1. they allow us to look the interaction of variables

2. they allow us to use fewer participants without sacrificing power

a situation in a factorial design or contingency table in which the effects of one independent variable depend on the level of another independent variable

the mean of all observations

the effect of one IV

the effect of one IV at one level of another IV

designs in which different subjects serve under the different treatment levels

experimental designs in which each subject receives all levels of at least one IV

experimental designs in which each participant produces multiple scores

1. normality in the distributions

2. homogeneity of variance

3. assumption of homogeneity of covariance: correlations among DV scores must be the same

1. avoids the problem of person-to-person variability

2. controls for extraneous variables

3. requires fewer participants then between-subjects designs to have same amount of power

1. order effect

2. carry-over effect

the effect on performance attributable to the order in which treatments were administered

the effect of previous trials (conditions) on a subject's performance on subsequent trials

an arrangement of treatment conditions designed to balance out practice effects

a statistical test often used for categorical data

-dv is number of observations

-is non-parametric

the chi-square goodness of fit test

a test for comparing observed frequencies with theoretically predicted frequencies

expected frequency

observed frequency

analysis of contingency tables using chi-square

a two-dimensional table in which each observation is classified on the basis of two variables simultaneously

ex: Walsh tested the effectiveness of using antidepressants after treatment for anorexia nervosa

(R-1)*(C-1)

independence of observations

one person's scores do not affect another person's scores

must equal the total of the rows, or the total of the columns

number of occurrences on one event divided by total number of occurrences of events

ratio of two risks

frequency of occurrence of one event divided by the frequency of occurrence of the other event

a study in which you select participants on the basis of some current condition and follow them into the future

ex: if you're interested in the relationship between smoking and cancer, and you find people who smoke and then track over time who develops cancer

a study in which you select participants on some criterion and then look back at their behavior in the past

ex: if you study the relationship between smoking and cancer and you examine data that already exist in terms of who smoked and developed cancer

you have to collect the data and analyze it

the data already exists and you just have to analyze it