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- University of North Dakota
- FINAL EXAM - Multiple Choice

Jillian K.

If a two-factor analysis of variance produces a statistically significant interaction, then you can conclude that...

the significance of the main effects is NOT related to the significance of the interaction.

The average verbal SAT score for the entire class of entering freshmen is 530. However, if you select a sample of 20 freshmen 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

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What is the mean for the following sample of scores?

Scores: 1, 2, 5, 4

M = 3

A positive value for a correlation indicates...

increases in X tend to be accompanied by increases in Y.

As the sample size gets larger, the size of the correlation necessary for significance...

gets smaller.

The distribution of sample means (for a specific sample size) consists of...

the sample means for all the possible samples (for the specific sample size)

Histogram

What is the value of (ΣX)² for the follwing scores?

Scores: 3, 0, 5, 2

100

Statistical methods that use sample data to answer general questions about a population are called...

Inferential Statistics

The value of the Pearson Correlation will be negative if...

SP is negative.

A researcher measures personality for a sample of n = 50 people and classifies each person as either Type A, Type B, or Type C personality. Which measure of central tendency would be appropriate to summarize these measurements?

Mode

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In analysis of variance, the F-ratio is a ratio of...

two variances

On an exam with a mean of μ = 70, you have a score of X = 65. Which of the following values for the standard deviation would you give the highest position within the class?

σ = 10

What is the median for the following set of scores?

Scores: 1, 2, 5, 6, 17

Mdn = 5

For a negatively skewed distribution with a mode of X = 25 and a median of 20, the mean is probably...

less than 20.

A researcher is conducting an experiment to evaluate a treatment that is expected to increase the scores for individuals in a population which is known to have a mean of μ = 80. The results will be examined using a one-tailed hypothesis test. Which of the following is the correct statement of the null hypothesis?

μ ≤ 80

Suppose the correlation between height and weight for adults is +0.80. What proportion (or percent) of the variability in weight can be explained by the relationship with height?

64 %

(.80)²

In general the distribution of F-ratios is...

positively skewed with all values greater than or equal to zero.

For an experiment comparing more than 2 treatment conditions you should use analysis of variance rather than separate t-tests because...

conducting several t-tests would inflate the risk of a Type I error.

A population has μ = 50 and σ = 5. If 10 points are added to every scoer in the population, then what are the new values for the new mean and standard deviation?

μ = 60 and σ = 5.

*The distribution just shifts

Even if a treatment has an effect it is still possible to obtain an extreme sample mean that is not very different from the original population mean. If this happens, you are likely to...

fail to reject the null, and make a Type II error.

For a population with μ = 80 and σ = 10, what is the z-score corresponding to X = 95?

+1.50

The symbol for SS stands for...

sum of squared deviations

In analysis of variance, each independent variable is referred to as a...

factor

The Pearson Correlation measures...

the degree of linear relationship

A population with μ = 85 and σ = 12 is transformed into z-scores. After the transformation, the population of z-scores will have a standard deviation of...

σ = 1.00

*SD is always 1.00 for z-scores

A researcher conducts an experiment comparing two treatment conditions and obtains 30 scores in each treatment. Which design would require the smallest number of participants?

a repeated-measures design

In a normal distribution...

the scores pile up in the middle and taper off symmetrically to both sides.

As a sample size increases...

- the value of
*df*also increases - the
*t*distribution becomes more like a normal distribution - the critical values of
*t*move to become smaller

For a distribution of scores, which of the following z-score values represents the location closest to the mean?

z = +0.50

Which of the following describes the typical chi-square distribution?

It is positively skewed, with no values less than zero.

Under what circumstances are post hoc tests necessary?

When you reject the null hypothesis with more than 2 treatment conditions.

A sample of n = 5 scores has M = 20 and s² = 4. What is the sample standard deviation?

s = 2

s = √4 = 2

In analysis of variance, the term factor refers to...

an independent (or quasi-independent) variable

A sample of n = 25 individuals is selected from a population with μ = 80 and a treatment is administered to the sample. If the treatment has no effect, then...

the sample mean should be close to 80 and should lead you to fail to reject the null hypothesis.

A negative value for a correlation indicates...

increases in X tend to be accompanied by decreases in Y.

If the results of a two-factor experiment are presented in a line graph, then an interaction can be seen whenever...

the lines move toward each other or cross

In analysis of variance, *MS *provides a measure of...

Variance.

The analysis of variance for a two-factor experiment produces...

3 separate F-ratios.

For any distribution, what is the z-score corresponding to the mean?

0

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

Using several t-tests increases the risk of a Type I error.

A population of N = 10 scores has a mean of μ = 80. If 5 points are added to every score in the distribution, what is the value of the new mean?

μ = 85

A z-score of z = -2.00 indicates a position in a distribution...

below the mean by a distance equal to 2 standard deviations.

Which set of test 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

The numerical value for a correlation...

can never be greater than 1.00 and can never be less than -1.00

The results from a two-factor analysis of variance show a significant main effect for factor A and a significant main effect for factor B. Based on this information, you can conclude that...

you cannot make any conclusions about the significance of the interaction.

A two-factor experimental study means that the study has...

two independent variables.

A college professor reports that students who finish exams early tend to get better grades than students who hold on to exams until the last possible moment. The correlation between exam score and amount of time spent on the exam is an example of...

a NEGATIVE correlation.

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

A. Comparing verbal skills for girls vs. boys at age 3

B. Comparing pain tolerance before and after taking a new pain medication

C. Comparing self-esteem for students who participate in school athletics vs. those who do not

D. Comparing problem solving skills for science majors versus art majors at a college.

B.

The null hypothesis for an ANOVA states that...

there are no differences between any of the population means.

If other factors are held constant, the standard error of *M* will _____ as the sample size increases.

decrease

A two-factor experiment means that the experiment design includes...

two independent variables.

The purpose for the post hoc tests is...

to determine which treatments are significantly different.

A two-factor study with 2 levels of factor A and 3 levels of factor B uses a separate group of n = 5 participants in each treatment condition. How many participants are needed for the entire study?

n = 30

*5 people per cell, 6 cells

For an extremely skewed distribution of scores, the best measure of central tendency would be...

the median.

Real limits are an important consideration when measuring a ______ variable.

continuous

Which of the following Pearson Correlations shows the greatest strength or consistency of relationship?

A. -0.90

B. +0.74

C. +0.85

D. -0.33

A.

Which of the following symbols identifies the sample standard deviation?

When very few subjects are available and individual differences are large.

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

the mean differences among the levels of one factor.

A sample of n = 20 scores is transformed into z-scores. The mean for the 20 z-scores is...

0

*z-score mean is always 0.

By selecting a smaller alpha level, a reasearcher is...

reducing the risk of a Type I error.

A professor recorded the academic major for each student in an introductory psychology class. If the data are presented in a frequency distribution graph, what type of graph should be used?

A bar graph.

An analysis of variance comparing three treatment conditions produces *df*_{total }= 24. For this ANOVA, what is the value of *df*_{between}?

2

*# of conditions - 1

What does it mean to obtain a negative value for the chi-square statistic?

The chi-square statistic can NEVER be negative.

Scores from a statistics exam are reported as deviations scores. Which of the following deviation scores indicates a higher position in the class distribution?

A. +8

B. 0

C. -8

D. cannot determine without more information

A

The amount of St. John's Wort given to each participant.

The results from a research study indicate that adolescents who watch more violent content on television also tend to engage in more violent behavior than their peers. The correlation between amount of TV violent content and amount of violent behavior is an example of...

a positive correlation.

A researcher is curious about the average level of science knowledge for high school seniors in the United States. The entire group of high school students in the U.S.A. is an example of...

population

If the null hypothesis is true and there is no treatment effect, what value is expected on average for the F-ratio?

1.00

The z-score boundaries for the critical region are determined by...

the alpha level

Although a research study is typically conducted with a relatively small group of participants known as a __________, most researchers hope to generalize their results to a much larger group known as a __________.

Sample, Population

In an experiment, the researcher manipulates the _______ and measures changes in the ________.

independent variable, dependent variable.

In a two-factor ANOVA, what is the implication of a significant A x B interaction?

The significance of the interaction has no implications for the main effects.

How many separate samples would be needed for a two-factor, independent-measures research study with 2 levels of factor A and 3 levels of factor B?

6

In an experiment, the researcher manipulates the _______ and measures changes in the ________.

independent variable, dependent variable.

In a two-factor ANOVA, what is the implication of a significant A x B interaction?

The significance of the interaction has no implications for the main effects.

6

In a frequency distribution graph, frequencies are presented on the ______ and the scores (categories) are listed on the ________.

Y axis, X axis

Two variables are said to interact when...

the effect of one independent variable dependson the levels of the second variable.

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