PSY 200 Unit 4
Using the Bonferroni post hoc test, to make all possible comparisons between the means of three groups while keeping the overall p level at 0.05, what should the p level be for each comparison?
.017
If the p level is 0.05 and the null hypothesis is true, what is the probability of making a Type I error (i.e., that one will fail to reject the null hypothesis)?
.05
If your p level is .05 and the null hypothesis is true, what is the probability that you will not make a Type I error (i.e., you will fail to reject the null hypothesis)?
.95
If the p level is.0.05 and the null hypothesis is true, the probability of making a Type I error when performing a single hypothesis test is _____, but if three hypothesis tests are performed, then the probability of NOT making a Type I error is _____, which means that the probability of making a Type I error at least once in these three hypothesis tests is _____.
0.95; 0.857; 0.143
In which situation would it NOT be appropriate to use a one-way ANOVA?
A researcher classifies a group of college students on the basis of their political leanings as liberal, conservative, libertarian, or green.
In which situation would it be necessary to use a within-groups ANOVA?
A researcher is interested in a longitudinal study that follows a group of kindergarten children through high school and assesses their body mass index at four time points.
Given a scale dependent variable and a nominal independent variable with three or more levels, a(n) _____ could be used to analyze the data.
ANOVA
When computing Tukey HSD with samples of different sizes, what additional step must be performed?
Calculate a weighted sample size called a harmonic mean.
An F statistic calculated on 2 and 26 degrees of freedom equals 2.23. Which decision should be made about a hypothesis tested at the p = 0.05 level?
Fail to reject the null hypothesis and conclude no significant differences are indicated among the groups.
The symbol for variance in ANOVA is:
MS, which stands for means square
F is obtained by dividing _____ by _____.
MSbetween/MSwithin
A researcher can't just run multiple t tests when the independent variable has more than two levels because as more statistical tests are run:
The probability of making a Type I error in one of the tests increases
If the cutoff q statistic is 4.96, with a p level of 0.05, which of these would be significant?
an HSD of 5.2
Within-groups variance reflects the:
average of sample variances
A measure of the differences among group means is:
between-groups variance
Interested in the effects of different kinds of instruction on videogame performance, Martin asks 30 college freshmen to each play an hour of Ratchet and Klank. Participants are randomly assigned to one of three instruction groups: (1) complete the tasks as quickly as possible, (2) conserve as much health as possible (i.e., play more carefully), or (3) find gold bolts (worth lots of money in equipment and ammunition). If Martin averages the scores for each instruction group and then compares them, any differences in the means of the instruction groups reflect:
between-groups variance
There is a different F distribution for every:
combination of sample size and number of samples.
The z, t, and F distributions have something in common—the numerator of the test statistic:
contains a measure of difference among group means.
Changes in within-groups variance result in changes in the _____ of the F ratio.
denominator
If between-groups variance is much larger than within-groups variance, we infer that the sample means are _____ one another, and we _____ the null hypothesis.
different from; reject
The F ratio is calculated by:
dividing a measure of between-groups variability by a measure of within-groups variability.
Within-groups degrees of freedom is calculated by:
for each condition, subtracting 1 from the number of subjects in that group and then adding together the totals for all the groups.
Violation of the assumption that samples are randomly selected affects researchers' ability to:
generalize the results of a study beyond the sample.
In Tukey's HSD post hoc test, the HSD stands for:
honestly significant difference
Cohen's d cannot be used as a measure of effect size for ANOVA because:
it only compares 2 means
According to Cohen's conventions, an R 2 of 0.19 is considered to be a(n) _____ effect size.
large
Homoscedasticity can be tested for by:
making sure that the largest sample variance is no more than two times the smallest variance
According to Cohen's conventions, an R 2 of 0.07 is considered to be a(n) _____ effect size.
medium
The assumptions of ANOVA are that samples are selected:
randomly, the population distribution is normal, and the samples come from populations with equal variances.
A post hoc test is warranted when one:
rejects the null hypothesis and there are more than two groups.
According to Cohen's conventions, an R 2 of 0.02 is considered to be a(n) _____ effect size.
small
If there are only two samples, then the F distribution is the:
square of the t distribution
The F ratio is a ratio of:
two variances
When F is significant:
we do not know which specific means differ significantly.
Interested in the effects of different kinds of instruction on videogame performance, Martin asks 30 college freshmen to each play one hour of Ratchet and Klank. Participants are randomly assigned to one of three instruction groups: (1) complete the tasks as quickly as possible, (2) conserve as much health as possible (i.e., play more carefully), or (3) find gold bolts (worth lots of money in equipment and ammunition). Obviously, even in a single instruction group, not all players will obtain the same final score. These differences in an instruction group reflect:
within-groups