Statistics Final.. Again.

On average, what vale is expected for the F-ratio if the null hypothesis is true?

1.00

A researcher reports t(12)=2.86, p<.05 for a repeated measures research study. How many individual participants in the study?

13

A repeated measures study using a sample of n=20 participants would produce a t-statistic with df= ________.

19

A researcher conducts a hypothesis test using a sample of n=20 from an unknown population. What is the df value for a one-sample t-statistic?

19

If an independent measures design is being used to compare two treatment conditions, then how many different groups of participants would be needed and how many scores would there be for each participant?

2 groups, 1 score each

With a=.01, the two-tailed critical region for a t test using a sample of n=16 subjects would have boundaries of ______.

2.947

A sample with a mean of M=40 and a variance of s^2=20 has an estimated standard error of 1 point. How many scores are in the sample?

20

A repeated measures study uses a total of n=10 participants to compare two treatment conditions. How many scores are measured in this study, and how many scores are actually used to compute the sample mean and the sample variance?

20 measured and 10 used

A researcher is using a two-tailed hypothesis test with a=.05 to evaluate the effect of a treatment. If the boundaries for the critical region are t=+or- 2.080, then how many individuals are in the sample?

22

A population has SS=100 and s^2=4. How many scores are there in the population?

25

An independent measures study uses n=15 participants in each group to compare two treatment conditions. What is the df value for the t-statistic for this study?

28 not 14.. so n=15, 15-1=14, 14x2=28

If the results of an experiment using t-ind were summarized as t(30)=2.817, p<.05, then you would know that the total number of participants used (N) was _________ and the null hypothesis was __________.

32; rejected

A research study comparing three treatments with n=5 in each treatment produces T1=5, T2=10, T3=15, with SS1=6, SS2=9, SS3=9, and (sum of)X^2=94. For this study, what is SStotal?

34

In a grouped frequency distribution, one interval is listed as 50-59. Assuming that the scores are measuring a continuous variable, what are the real limits for this interval?

49.5 and 59.5

A research report concludes that there are significant differences among treatments, with "F(2,24)=8.62, p<.01." If the same number of participants was used in all of the treatment conditions, then how many individuals were in each treatment?

9

What kind of frequency distribution graph shows the frequencies as bars, with no space between adjacent bars?

A histogram

Which set of characteristics will produce the smallest value for the estimated standard error?

A large sample size and a small sample variance

The normal distribution is an example of

A smooth curve showing data from a population

A hypothesis test produces a t-statistic of t=2.20. If the researcher is using a two-tailed test with a=.05, how large does the sample size have to be in order to reject the null hypothesis?

At least 13

A researcher surveys a sample of n=200 college students and asks each person to identify his or her favorite movie from the past year. If the results were presented in a frequency distribution graph, what kind of graph would be appropriate?

Bar graph

In an analysis of variance, differences caused by treatment effects contribute to which of the following variances?

Between treatments variance but not within treatment variance

In an analysis of variance, differences between participants contribute to which of the following variances?

Both between treatments variance and within treatments variance

For which of the following situations would a repeated measures research design be appropriate?

Comparing pain tolerance with and without acupuncture needles

In a directional one-sample t-test, the rejection region is located in _________ of the sampling distribution of t.

Either the left or the right tail, but not both tails

For a research study comparing attitude scores for males and females, participant gender is an example of what kind of variable?

Independent variable

Compared to an independent measures design, a repeated measures study is more likely to find a significant effect because it reduces the contribution of variance due to __________.

Individual differences

For the two factor between subjects ANOVA, what is calculated in stage 2 of the equation?

Interaction variance and factor a and factor b variability

After measuring two individuals, a researcher can say that Tom's score is 4 points higher than Bill's. The measurements must come from a(n) _____ scale.

Interval or ratio

If a set of scores is displayed in a frequency polygon, what scale of measurement was used to measure the scores?

Interval or ratio

When n is small (less than 30), how does the shape of the t distribution compare to the normal distribution?

It is flatter and more spread out than the normal distribution

Which of the following describes what a confidence interval does?

It uses a sample mean to estimate the corresponding population mean

If other factors are held constant, what is the effect of increasing sample size?

It will decrease the estimated standard error and increase the likelihood of rejecting Ho

In general, what factors are most likely to reject the null hypothesis for an ANOVA?

Large mean differences and small variances

Which combination of factors is most likely to produce a significant value for an independent measures t-statistic?

Large samples and small variance

On average, what value is expected for the F-ratio if the null hypothesis is false?

Much greater than 1.00

The students in a psychology class seemed to think that the midterm exam was very easy. If they are correct, what is the most likely shape for the distribution of exam scores?

Negatively skewed

Students in an introductory art class are classified as art majors and non-art majors. What scale of measurement is being used to classify the students?

Nominal

In a repeated measures experiment, each individual participates in one treatment condition and then moves on to a second treatment condition. One of the major concerns in this type of study is that participation in the first treatment may influence the participant's score in the second treatment. What is this problem called?

Order effects

Using letter grades (A,B,C,D and E) to classify student performance on an exam is an example of a _____ scale of measurement.

Ordinal

A researcher uses an anonymous survey to investigate the television viewing habits of american adolescents. The goal of the research is to determine the average number of hours each day that american adolescents spend watching television. The researcher is trying to determine a number that is an example of a ________.

Parameter

A population of scores has a mean of myuh=26, a median of 23, and a mode of 22. What is the most likely shape for the population distribution?

Positively skewed

What term is used to describe the shape of a distribution in which the scores pile up on the left hand side of the graph and taper off to the right?

Positively skewed

Which of the following describes a typical distribution of F-ratios?

Positively skewed with all values greater than or equal to zero

What kind of measurement scale is necessary to conclude that one score is twice as big as another?

Ratio

A researcher plans to conduct a research study comparing two treatment conditions with a total of 20 participants. Which of the following designs would produce 20 scores in each treatment?

Repeated measures design

A researcher is interested in the eating behavior of rats and selects a group of 25 rats to be tested in a research study. The group of 25 rats is an example of a _________.

Sample

In an analysis of variance, what is measured by the MS values?

Samples variance

The average verbal SAT score for the entire class of entering freshman is 530. However if you select a sample of 20 freshman and compute their average verbal SAT score you probably will not get exactly 530. What statistical concept is used to explain the natural difference that exists between a sample mean and the corresponding population mean?

Sampling error

A characteristic, usually a numerical value, which describes a sample is called a _________.

Statistic

What was the pen name of William Sealy Gosset, the creator of the t-distribution?

Student

What is the final step to be performed when computing (sum of)(x-2)^2?

Sum the squared values

A researcher conducts an experiment to determine whether moderate doses of St. Johns Wort have any effect on memory for college students. For this study, what is the independent variable?

The amount of St. Johns Wort given to each participant

In a two-factor analysis of variance, a main effect is defined as _______.

The mean differences among the levels of one factor

a sample has a mean of M=86. If one new person is added to the sample, what effect will it have on the sample mean?

The sample mean will increase

What additional information is obtained by measuring two individuals on an interval scale compared to an ordinal scale?

The size of the difference

In an ANOVA, what is represented by the letter T?

The sum of the scores in a specific treatment

What is assumed by the homogeneity of variance assumption?

The two samples have equal variances

For an ANOVA comparing three treatment conditions, what is stated by the null hypothesis?

There are no differences between any of the population means.

A 2x6x3 Factorial ANOVA indicates that

There are three independent variables, one of which has 6 levels

In an independent measures ANOVA, individual differences contribute to the variance in the numerator and in the denominator of the F-ratio. For a repeated measures ANOVA, what happens to the individual differences in the denominator of the F-ratio?

They are measured and subtracted out in the second stage of the analysis

What is the purpose for post hoc tests?

To determine which treatments are significantly different

When comparing more than two treatment means, why should you use an analysis of variance instead of multiple t-tests?

Using several t-tests increases the risk of a type 1 error

For which of the following situations would a repeated measures design have the maximum advantage over an independent measures design?

When very few subjects are available and individual differences are large

Which set of scores has the smallest standard deviation?

a: 11,17,31,53 b: 5,11,42,22 c: 145,143,145,147 d: 27,105,10,80 C is correct

In the first stage of a repeated measures ANOVA, total degrees of freedom is partitioned into ________.

between treatments df and within treatments df

Which of the following is the correct way to report the results of a hypothesis test and a measure of effect size using a t-statistic?

t(19)=2.30, p<.05, r^2=0.42