Statistics For Psychology

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

A. -0.90

If an entire population with μ = 60 and σ = 8 is transformed into z-scores, then the distribution of z-scores will have a mean of ___ and a standard deviation of ___.

A. 0 and 1

For a sample of n=16 individuals, how large a Pearson's correlation is necessary to be statistically significant for a two tailed test with alpha level=.05

A. 0.497

A sample consists of n=16 scores. How many scores are used to calculate the range?

A. 2

An independent measures study has one sample with n=10 and a second sample with n=15, to compare two experimental treatments. What is the df value for the t statistic for this study?

A. 23

For an independent measures ANOVA comparing three treatments with a sample of n=5 in each treatment, what is the critical value for the f-ratio using an alpha level of .05?

A. 3.88

For a perfectly symmetrical distribution with a median of 30, what is the value of the mean?

A. 30

A researcher conducts a hypothesis test using a sample of n=40 from an unknown population. What is the df value of the t statistic

A. 39

The data from an independent measures research study produces a sample mean difference of 6 points and an estimated standard error of 2 points. If there are n=8 in each sample, then the value of the t statistic is

A. 6/2

After every score in a sample is multiplied by 3, the mean is calculated and found to be M=21. What is the mean for the origional scores?

A. 7

What is the value of €X + 1 for the following scores Scores= 1,0,2,4

A. 8

A researcher measures driving distance from college and weekly cost of gas for a group of commuting college students. What kind of correlation is likely to be obtained for these two variables?

A. A positive correlation

The relationship between a statistic and a parameter is the same as the relationship between________?

A. A sample and a population

Which is indicated by a Pearson correlation of r=+1.00 between x and y

A. Each time X increases, there is a perfectly predictable increase in Y

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

A. Factor

Which of the following correctly describes the effect of increasing the alpha level (for example from .01 to .05)

A. Increase the likely hood of rejecting Ho and increasing the risk of Type I error

For the independent measures t statistic, what is the effect of increasing the difference between sample means?

A. Increases the likelihood of rejecting Ho and increase measures of effect size

Which of the following accurately describes an independent measures study?

A. It uses a different group of participants for each of its treatment conditions being compared

If the mean and variance are computed for each sample in an independent-measures, two-factor experiment, which of the following types of sample data will tend to produce large F-ratios for the two-factor ANOVA?

A. Large differences between sample means and small sample variances

A population with a mean of m= 6 has €X = 42. How many scores are in the population

A. N= 7

What is the shape for the distribution shown in the accompanying graph? 1, f= 3 2, f= 4 3, f= 3 4, f= 2 5, f= 1

A. Positively skewed

A researcher conducts a repeated measures study to evaluate a treatment with a sample of n=16 participants and obtains a t statistic of t=1.94. The treatment is expected to increase scores and the sample mean shows an increase. Which of the following is the correct decision for a hypothesis test using alpha levels =.05?

A. Reject the null hypothesis with a one tailed test but fail to reject with two tails

An independent measures research study uses two samples each with n=12 participants. If the data produces a t statistic of t=2.50, then which of the following is the correct decision for a two tailed hypothesis test?

A. Reject the null hypothesis with alpha=.05 but fair to reject with alpha = .01

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

A. Sample, Population

Two variables are said to interact when_____

A. The effect of one independent variable depends on the levels of the second variable

In a 2 factor Analysis of variance a main effect is defined as

A. The mean difference among the levels on one factor

A researcher conducts a hypothesis test to evaluate the effect of a treatment. The hypothesis test produces a z-score of z=2.37. Assuming the researcher is using a two tailed test, what decision should be made?

A. The researcher should reject the null hypothesis with alpha levels =.05 but not with .01

When comparing more than 2 treatment means, why should you use an analysis of variance instead of using several t tests?

A. Using several t tests increases the risk of a type I error

Scores on the SAT form a normal distribution with mean 500 and standard deviation 100. What is the minimum SAT score needed to be in the top 60% (i.e., 40th percentile) of the distribution?

A. X= 475

A sample of n=8 scores has a mean of M=10. After one score is removed from the sample, the mean for the remaining scores is found to be M=11. What was the score that was removed

A. X=3

For a population with µ= 60, which of the following values for the population standard deviation would cause X=68 to have the most extreme position in the distribution?

A. o=1

What z-score value separates the top 10% of a normal distribution from the bottom 90%?

A. z= 1.28

The results of an independent measures research study are reported as "t(20)= 2.12, p<.05 two-tailed test", For this study, what t values formed the boundaries for the critical region?

B. +/- 2.086

A sample of n=16 individuals is selected from a population with µ= 60 and o=6 and a treatment is administered to the sample. After treatment the sample mean is M=63. What is the value of Cohens D for this sample

B. 0.50

For a research study with 2 levels of factor A, and 3 levels of factor B, and n=5 in each treatment condition, what are the df values for the F-ratio evaluating the main effect for factor A

B. 1,4

An independent measures study comparing two treatment conditions produces a t statistic with df=18. If the two samples are the same size, how many participants were in each of the samples

B. 10

What is the value of SS (Sum of squared deviations) for the following sample? Sample= 2, 3, 4, 7

B. 14

What value for the missing mean would result in no AxB interaction B1 B2 A1 20 30 A2 10 X

B. 20

An analysis of Variance produces (SS between)=40, and (MS between)=20. In this analysis, how many treatment conditions are being compared?

B. 3

The following table shows the results of a 2 factor analysis of variance with 2 levels of factor A and 3 for B with n=5 participants per condition. What is the f-ratio for the AxB interaction?

B. 4

For an experiment involving 3 levels of factor A and 3 levels of Factor B, with a sample of n=8 in each treatment condition, what are the df values for the f-ratio for the AxB interaction

B. 4,63

AN independent measures research study compares three treatment conditions using a sample of n=5 in each treatment. For this study, the three samples have SS1=10, SS2= 20, SS3=15. What value would be obtained for MS within?

B. 45/12

An analysis of variance produces (SS total)=80 and (SS within)=30. For this analysis what is (SS between)

B. 50

What is the value of the median for the following set of scores? Scores= 1, 3, 4, 6, 7, 8, 12, 23

B. 6.5

A set of n=15 pairs of scores (x and y values) has SSx=4, SSy=25 and SP=6. The Pearson correlation for these data is

B. 6/10

An analysis of variances produces (DF between)=3 and (df within)=24. If each treatment has the same amount of participants, how many were used in each treatment?

B. 7

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______

B. A negative Correlation

What is stated by the alternative hypothesis for an ANOVA?

B. At least one of the population means is different from another

Which of the following best describes the Pearson correlation for these data X Y 2 5 5 1 3 4 4 2

B. Is negative

As the sample size gets larger, what happens to the size of the correlation that is needed for significance

B. It gets smaller

In general, if the variance of the difference scores increases, then what will happen to the value of the t statistic

B. It will decrease (Move towards 0 at the center of the distribution)

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

B. Large sample and small variance

If a frequency distribution is shown in a bar graph, which scale was used to measure the scores

B. Nominal or Ordinal

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 participants score in the second treatment. This problem is called

B. Order Effects

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

B. Ordinal

A two tailed hypothesis test is being used to evaluate a treatment effect with alpha level .05. If the sample data produces a z-score of z=2.24, then what is the correct decision

B. Reject the null hypothesis and conclude that the treatment has an effect

A hypothesis test with a sample of n= 25 participants produces a t statistic of t = +2.53. Assuming a two tailed test with the critical region in the right hand tail, what is the correct decision?

B. The researcher can reject the null hypothesis with either a .05 or .01 alpha level

In an independent measures hypothesis test, what must be true if t=0

B. The two sample means must be equal

With alpha level=.05, and df=8, the critical values for a two tailed t test are t=+/- 2.306. Assuming all other factors are held constant, if the df value were increased to df=20, what would happen to the critical value of t?

B. They would decrease (Move closer to 0)

A researcher administers a treatment to a sample of participants selected from a population with µ=80. If the researcher obtains a sample mean of M=88 which combination of factors is most likely to result in rejecting the null hypothesis?

B. o=5 and n-50

A set of n=15 pairs of scores (X and Y values) produces a correlation of r=0.40. If each of the x values is multiplied by 2 and the correlation is computed for the new scores, what value will be obtained for the new correlation?

B. r=0.40

What is the value of SP for the following set of data? X Y 1 4 2 4 9 1

C. -15

What proportion of a normal distribution is located between the mean and z= 1.40?

C. 0.4192

One sample has M= 18 and a second sample had M=14. If the pooled variance for the two samples is 16, then what is the value of Cohen's d?

C. 1.00

What is the variance for the following population of scores? Scores= 5, 2, 5, 4

C. 1.50

A research report concludes that there are significant differences among tratments, with F(2,27)= 8.62, p<.01. If the same number of participants was used in all of the treatment conditions, then how many indiciduals were in each treatment?

C. 10

A researcher report describing the results from a repeated measures study states: The data shows no significant difference between the two treatments, t(10)=1.65, p>.05. Based on this report, you can conclude that a total of ____ Individuals participated in the research study.

C. 11

What is the value of SS (sum of squared deviations) for the following population? Population= 1,1,1, 5

C. 12

A population distribution has s=6. What position i this distribution is identified by a z-score of z= + 2.00?

C. 12 points above the mean

What is the total number of scores for the distribution shown in the following table? 1, f= 2 2, f= 4 3, f= 5 4, f= 3

C. 14

Which set of scores has the smallest standard deviation?

C. 145, 143, 145, 147

The results of a single sample t test are reported as following : t(15)=2.70, p<.05. Based on this report, how many individuals were in the sample?

C. 16

Suppose the correlation between height and weight for adults is +0.40. What proportion (or percent) of the variability in weight can be explained by the relationship with height?

C. 16%

A sample of n=4 scores has €X= 8 and €X² =40. What is the value of SS for this sample?

C. 24

The results of a 2factor analysis of variance produce df=1,30 for the f-ratio for factor A and df=2, 30 for the f ratio for the AxB interaction. Based on this info, how many levels of factor B were compared in the study

C. 3

How many separate F ratios are used in a two factor ANOVA

C. 3 overall f-ratios

A researcher reports an f-ratio with df=2,18 from an independent measures research study. Based on the df values, how many treatments were compared in the study and what was the total number of subjects?

C. 3 treatments and 21 subjects

What is the mean for the following sample of scores? Scores= 1,4,5,10

C. 5

What is the missing value for the f-ratio SS df MS Between 30 XX XX Within XX XX XX F=XX Total 62 XX

C. 5.00

A researcher measures IQ and weight for a group of college students. What kind of Correlation is likely to be obtained for these two variables?

C. A Correlation near zero

A researcher administers a treatment to a sample of participants selected from a population with µ=80. If a hypothesis test is used to evaluate the effect of the treatment, which combination of factors is most likely to result in rejecting the null hypothesis?

C. A sample mean much different than 80 with an alpha level=.05

A two-factor research study is used to evaluate the effectiveness of a new blood pressure medication. In this two-factor study, factor a is medication versus no medication and factor B is male versus female. The medication is expected to reduce blood pressure for both male and females, but it is good to have a much greater effect for males. What pattern of results should be obtained if the medication works as predicted?

C. A significant main effect for Factor A and a significant interaction

Which combination of factors will increase the chances of rejecting the null hypothesis?

C. A small standard error and a large alpha level

Ina line graph showing the results from a two factor experiment, the levels of factor B are presented on the x-axis and separate lines are used to display the means for A1 and A2. If the points on the line for A1 are consistently 5 points higher than the corresponding point on the line for A2, what pattern of results is indicated?

C. An indication of an A-effect but no indication of an interaction

Even if a treatment has an effect, it is still possible to obtain a sample mean that is very similar to the original population mean. What outcome is likely if this happens?

C. Fails to reject Ho and makes a type II error

What scale of measurement was used to measure the scores in the distribution shown in the accompanying graph? ( Bar graph but all of its touching)

C. Interval or Ratio

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

C. Large mean difference and small variances

Which correlation should be used to measure the relationship between gender and grade point average for a group of college students

C. Point Based correlation

A researcher uses an anonymous survey to investigate the study habits of American college students. The entire group of American College students is an example of a _____

C. Population

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 diffences that exists between a sample mean and the corresponding population mean?

C. Sampling Error

A researcher obtains a Pearson correlation of r=0.43 for a sample of n=20 participants. For a two tailed test, which of the following accurately describes the significance of the correlation?

C. The correlation is not significant with either alpha levels of .05 or .01

Last week Sarah had exams in math and in Spanish. On the math exam, the mean was µ= 40 with s = 5, and Sarah had a score of X = 45. On the Spanish exam, the mean was µ= 60 with s = 8, and Sarah had a score of X = 68. For which class should Sara expect the better grade?

C. The grades should be the same because the two exam scores are in the same location

For an independent measures research study, what is measured by Cohen's d or r²

C. The size of the difference between the two treatments

What is the purpose for post HOC tests?

C. To determine which treatments are significantly Different

Under what circumstances is the phi-coefficient used?

C. When both X and Y are dichotomous variables

A sample of n=5 scores has a mean of M=8. One new score is added to the sample and the new mean is calculated to be M=9. What is the value of the new score?

C. X= 14

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

C. a Quasi independent variable

An independent-measures study produces sample means of M1=35 and M2=31 and a pooled variance of 25. For this study, Cohens D=______

C. d= 4/5

If other factor are held constant, which set of sample characteristics is most likely to produce a significant t statistic?

C. n=100, s²=100

A researcher conducts a hypothesis test using a sample from an unknown population. If the t statistic has df=35, how many individuals were in this sample?

C. n=36

A sample of n=20 scores has a mean of M= 45 and a standard deviation of s= 8. In this sample, what is the z-score corresponding to X= 5?

C. z= 1.50

An analysis of variance produces (SS between)=30, (SS within)=60 and an f ratio with df=2,15. For this analysis what is the F ratio?

C.15/4=3.75

For the distribution in the accompanying graph, what is the value of €X Scores= 1, 2, 2, 3, 3, 3, 3, 4, 4, 5

C= 30

In a 2 factor ANOVA, what is the implication of a significant AxB Interaction?

D. The significance of the interaction has no implication for the main effects

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

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

What proportion of a normal distribution is located between z= -0.25 and z = +0.25?

D. 0.1974

John drives to work each morning and the trip takes an average of µ= 38 minutes. The distribution of driving time is approximately normal with a standard deviation of o=5 minutes. For a randomly assigned morning, what is the probability that johns drive to work will take between 36 and 40 minutes?

D. 0.3108

How many separate groups of participants would be needed for an independent measures, two factor with 3 levels of Factor A and 4 levels of factor B?

D. 12

A repeated measures study and an independent ,measures study both produced a t statistic with df=16. How many individuals participated in each study?

D. 17 for repeated measures and 18 for independent measures

For the population of scores shown in the frequency distribution table, the mean is_____ X Y 5 2 4 1 3 3 2 2 1 2

D. 29/10 = 2.90

The following data represents the means for each treatment condition in a 2 factor experiment. Note that one mean is not given. What value for the missing mean would result is no main effect for factor B? B1 B2 A1 20 10 A2 40 X

D. 50

What is the value of (€X)² for the following scores? Scores = 1, 5, 2

D. 64

The classroom in the Psychology department are numbered from 100-108. A professor records the number of classes held in each room during the fall semester. If these values are presented in a frequency distribution graph, what kind of graph would be appropriate?

D. A bar graph (Being numbered 100-108 makes it nominal)

If a repeated-measures study shows a significant difference between two treatments with α = .01, then what can you conclude about measures of effect size?

D. A significant effect does not necessarily mean that the effect size will be large

By selecting a larger alpha level, a researcher is______

D. All of the above (Attempting to make it easier to reject Ho, Be better able to detect a treatment effect, and increasing the risk of a type I error)

If the sample mean difference is 3 points, which of the following sets of data would produce the largest value for Cohen's d?

D. Cohens d is the same for all three samples

What is the consequences of a type I error?

D. Concluding that a treatment has an effect when it really has no effect

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

D. Individual differences

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.

D. Interval or ratio

A sample has a mean of M=39.5 and a standard error of s= 4.3, and produces a t statistic of_____. For a two tailed hypothesis test with alpha level= .05, what is the correct statistical decision for this sample?

D. It is impossible to make a decision about Ho without more information

How does sample variance influence the likelihood of rejecting the null hypothesis and measures the effect size such as r² and Cohen's d?

D. Larger variance decreases both the likelihood and measures of effect size

For an exam with a mean of M=74 and a standard deviation of s=8, Mary has a score of X = 10, Bob score corresponds to Z = +1.50 and Sue's scores located above the mean by 10 points. If the students are placed in order from smallest to largest score, what is the correct order

D. Mary, Sue, Bob

For an experiment comparing 2 methods for teaching social skill training to autistic children, the independent variable is ______ and the dependent variable is _______.

D. Teaching methods, the social skills that are learned

If the results of a two-factor experiment are presented in a line graph, then what pattern appears in the graph if there is an interaction?

D. The lines move towards each other or cross

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

D= +1.50

For a two tailed hypothesis test evaluating a Pearson correlation, what is stated by the null hypothesis?

The population correlation is zero

What is the consequence of a type II error?

c. Concluding that a treatment has no effect when it really does