Statistics Expert Q&A

After conducting a one-sample Z-test,you arrived at a value of 5.7 for the z value.What is your conclusion?

A) Reject the null hypothesis.
B) Accept the null hypothesis.
C) The result is too close to call.
D) You have miscalculated.

Tests of homogeneity are used to compare several binomial populations.

Another school district also planned to evaluate two different workbooks and two distinct teaching machines to assess their effectiveness in teaching the concept of multiplication. However, the administrators in this school district consulted a statistician about the design of their study. Because they were looking for a method effective on children of all abilities, the statistician suggested they check the children's past scholastic records and divide the children into groups according to their ability level. These ability groups represent relatively homogeneous experimental units within which the comparison of teaching methods may be made. She assigned one child from each ability level to each teaching method. Twenty students participated in the study. After receiving instruction, the children took a multiplication test and the number of errors they made were recorded. What experimental design did the statistician use?
________________________________________________________
The null and alternate hypotheses are as follows: : The three population distributions are identical. : At least two of the three population distributions differ in location.
Describe what the test statistic is.
________________________________________________________
Test Statistic: = ______________
Reject Region:
Reject if F > ______________
Conclude: ______________
The teaching methods ______________ equally effective.
Estimate the observed significance level of this test.
______________

The nonparametric counterpart of the parametric t-test of for matched pairs is the:

A) Friedman test
B) Kruskal-Wallis test
C) Wilcoxon signed rank test
D) Wilcoxon rank sum test
E) chi-square test

A chi-square test for independence with 10 degrees of freedom results in a test statistic of 17.894. Using the chi-square table, the most accurate statement that can be made about the p-value for this test is that 0.05 < p-value < 0.10.

The four most popular flavors of a particular brand of ice cream are French Vanilla, Natural Vanilla, Chocolate Chip and Caramel Almond Swirl. The question arose as to whether each of these flavors is equally preferred. To answer that question, a random sample of 160 sales was selected, yielding the following data: Compute the value of the test statistic.
What is ?
______________
Set up the appropriate rejection region for = 0.05.
Reject when > ______________.
What is the appropriate conclusion?
Conclude that the ice cream flavors ______________ equally preferred.

A pollster was interested in determining whether three television dramas are equally preferable among men and women. The following data was recorded: Compute = ______________
Reject when > ______________.
Conclude that the preference of television drama is ______________ the viewer's gender.

The Wilcoxon signed rank test is applied to compare two populations, when the samples are matched pairs and the data are interval but not normally distributed.

The Kruskal-Wallis test can be used to test for a difference between two populations. It will produce the same outcome as the two-tail Wilcoxon rank sum test.

A study of educational levels of 500 voters and their political party affiliations in a southern state in the USA showed the following results: Use the 1% level of significance and test to see if party affiliation is independent of the educational level of the voters. = ______________
Critical Value = ______________
Conclusion: ______________
Political party affiliation ______________ on the educational level of the voters.

The mean of the sampling distribution of the difference is equal to one.

If you have a sample size of 16 and a population standard deviation of 40,what is your standard error of the mean?

A) -10
B) 10
C) 5
D) -5

Which of the following is not a characteristic of a multinomial experiment?

A) The experiment consists of a fixed number, n, of trials.
B) The outcome of each trial can be classified into one of two categories called successes and failure.
C) The probabilitythat the outcome will fall into cell i remain constant for each trial.
D) Each trial of the experiment is independent of the other trials.
E) The experiment consists of a fixed number, n, of trials and the outcome of each trial can be classified into one of two categories called successes and failure.

The Wilcoxon signed rank test for matched pairs is the nonparametric counterpart of the paired two-sample t-test of .

The Spearman rank-correlation is a nonparametric test that 1) uses the directions of differences observed in a matched-pairs sample to determine whether the relative frequency distributions of two statistical populations are identical to or different from one another and 2) determines whether a sample comes from a population with a specified median.

A supermarket chain has its own house brand of ice cream. The general manager claims that her ice cream is better than the ice cream sold by a well-known ice cream parlor chain. To test the claim 40 individuals are randomly selected to participate in the following experiment. Each respondent is given the two brands of ice cream to taste (without any identification) and asked to judge which one is better. Suppose that 25 people judge the ice cream parlor brand better, four say that the brands taste the same, and the rest claim that the supermarket brand is better. Can we conclude at the 1% significance level that the general managers' claim is false?
Test statistic:
z-statistic = ______________
Rejection region:
Reject if the z-statistic ______________.
Conclusion: ______________
We ______________ conclude at the 1% significance level that the general managers' claim is false.
What is the p-value for the above test?
______________

A vendor was interested in determining whether two soft drink machines dispense the same amount of liquid. A sample of size seven was selected from each machine and the amount of liquid dispensed (in ounces) was recorded as Use the Wilcoxon rank sum test to determine whether the distributions for the amount of liquid dispensed are the same for both machines. Use = 0.05.
The null and alternate hypotheses are: : The distributions for the amount of liquid dispensed are identical for the two machines. : The distributions for the amount of liquid dispensed differ for the two machines.
What is the test statistic?
T:______________
What is the critical value for the test statistic?
______________
Thus: ______________
Conclude:
We conclude that the distributions of the amount of liquid dispensed by the two machines are ______________.

In applying the chi-square goodness-of-fit test, the rule of thumb for all expected frequencies is that each expected frequency is 5 or more.

The Wilcoxon rank-sum test is a nonparametric test that uses two independent simple random samples to determine whether the relative frequency distributions of two statistical populations of continuous values are identical to or different from one another.

Which of these strategies is MOST commonly used to decrease type II error?

A) using a non-directional (two-tailed) alternative hypothesis (H₁)
B) using a directional (one-tailed) null hypothesis (H₀)
C) increasing sample size
D) lowering alpha