RUTGERS quantitative methods in psychology exam 2 (kilianski)

Pearson's r

finds correlation between IV and DV

values of r

values range from -1 to 1; 0 means no correlation

Pearson's r null hypothesis

Ho: r(population) = 0

In a Pearson's r test, there is no restriction between of range within the range of possible values.

true

In a Pearson's r test, a significant correlation means there is a causal relationship between the IV and DV.

false

Coefficient of determination

r squared; effect size in a Pearson's r test; tells you what percent of the variability in the DV is accounted for by the IV

Paired Samples t-test

used for repeated measures in experiments; DV is measured, experimental manipulation is administered, DV is measured again

When retesting subjects, an independent samples t-test is not acceptable because scores within subjects are correlated.

true

Why is the SEd different in a paired samples t-test than an independent sample?

we must take within-subjects correlation into account (if significant)

one-way ANOVA test

finding differences between three or more sample means; finds ratio of variability between and within groups

one-way analysis of variance (ANOVA) null hypothesis

Ho: μ1 = μ2 = μ3...

In finding the difference between three or more means, you cannot use multiple t-tests because the probability of falsely accepting the null hypothesis increases with each test.

false; more likely to falsely reject the null hypothesis

Tukey's HSD

used when there is a significant difference to find the specific mean difference; only used in a one-way ANOVA or a factorial ANOVA for every significant F with three or more levels

SS(w)

find the mean for each level of the IV; subtract it from each individual score; square those differences; sum the squares; add the values together

SS(b)

find each condition mean; subtract the grand mean from each condition mean; square these differences; multiply them by the sample size for that condition; add those values together

The bigger the differences between conditions are, the bigger the sum of squares between will be.

true

factorial analysis of variance (ANOVA)

compares means across two or more IVs

"main effect" in a factorial ANOVA

effects of IVs seperately

"interaction" in a factorial ANOVA

effects of different combinations of IVs

2 x 2 ANOVA

two IVs with two levels each

2 x 3 ANOVA

two IVs, one of which has two levels and one of which has three

When both the independent and dependent variables are interval/ratio level, which statistical test should be used?

Pearson's r

Why is the term 2r(SEM1)(SEM2) not included in the independent samples t-test?

r is assumed to be 0 in the independent samples t-test

The term -2r(SEM1)(SEM2) in the paired samples t-test causes the t-ratio to be ________ than it would if the term were excluded.

larger

With respect to the paired-samples t-test, as the size of the r increases, the t-ratio _____ making it ________ to reject the null hypothesis.

increases; more likely

If the Pearson's r between variables X and Y is -.50, how much of variance in Y can be predicted by X?

25%

Which of the following is used in determining the degrees of freedom between in the F-test?

the number of groups being compared

In the F statistic, the sum of squares between is influenced by

differences between each group mean and the grand mean

In an experiment, the numerator in the F statistic is a measure of

the effect of the IV on the DV

In a one-way ANOVA, as the sum of squares within increases, the probability of accepting the null hypothesis

increases

If the F statistic is significant in the 1-way ANOVA, the next step to take would be

to reject the null hypothesis and conduct a post-hoc test

Why do we conduct a post-hoc test if we find a significant F in a one-way ANOVA?

Because you don't know which means differ from which other ones when there are more than two of them.

Assuming that the mean differences and standard deviations are constant, you are less likely to reject the null hypothesis when using a paired-samples t-test than an independent samples t-test.

false

In a 1-way ANOVA, if the sum of squares between remains constant and the number of means being compared increases, you are more likely to find a significant difference among the means.

true

In an ANOVA, both the number of levels of the independent variable and the size of the sample influence the degrees of freedom within.

true

The reason there is only one number shown for degrees of freedom in any t-test is because the degrees of freedom between must always be 1.

true

For an independent samples t-test and a paired samples t-test with same number of subjects, the degrees of freedom would be the same.

false

With respect to a factorial ANOVA, if both main effects are significant, the interaction must also be significant.

false

In a factorial ANOVA, when neither main effect is significant, the interaction may still be significant.

true

When an ANOVA results in the rejection of the null hypothesis, the between-group variability must be greater than the within-group variability.

true

An interaction can only occur between ___ or more ___ variables

two; independent

In an analysis of variance, total variability results from the accumulated differences between each individual score and the _____.

grand mean

In an analysis of variance, between group variability results from the accumulated differences between each sample mean and the ___.

grand mean

In an analysis of variance, within group variability results from the accumulated differences between each individual score and the ___.

group mean

When a calculated F ratio has a large value, it indicates that the variability between groups is ___ than the variability within groups.

larger

The variance, or mean square, results from diving the sum of squares by ___.

degrees of freedom

mean square

estimates of variance across groups; SS/df

Type I error

incorrect rejection of a true null hypothesis

Type II error

incorrect acceptance of a false null hypothesis

The total sum of squares is made up of two major components, the ___ and the ___.

SS(w); SS(b)

When an ANOVA results in the rejection of the null hypothesis, then the ___ variability must be larger than the ___ variability.

between group; within group

If the within group variability is small, then the separate sample groups are most likely to have ___ distributions.

leptokurtic

A five-group research design with six subjects in each group has ___ between degrees of freedom and ___ within degrees of freedom.

4; 25

The greater the spread among the various sample means, the larger is the ___ variability.

between group

The F ratio is a non directional, two-tail test of differences among sample groups used whenever the data are in interval form.

true

ANOVA demands that at least four sample groups must be compared.

false

On a four-group design, the between degrees of freedom for a one-way ANOVA must equal 4.

false

ANOVA assumes that the data are at least interval.

true

An F ratio of 5.00 indicates that the variance between groups is five times greater than the variance within groups.

true

The use of the factorial ANOVA is required whenever there is more than one independent variable and the data are in interval form.

true

On a factorial ANOVA, the interaction effect will always be significant if the main effects are themselves significant.

false

To do a factorial ANOVA, there must be a minimum of at least four different treatment conditions.

true

When the obtained value of F is larger than the table value of F for a given number of degrees of freedom, the null hypothesis cannot be rejected.

true