Who talks more—men or women? Researchers equipped random samples of 56 male and 56 female students from a large university with a small device that secretly records sound for a random 30 seconds during each 12.5-minute period over 2 days. Then they counted the number of words spoken by each subject during each recording period and, from this, estimated how many words per day each subject speaks. The female estimates had a mean of 16,177 words per day with a standard deviation of 7520 words per day. For

the male estimates, the mean was 16,569 and the standard deviation was 9108. Do these data provide convincing evidence at the α=0.053051526=0.200=20.0%α=0.05significance level of a difference in the average number of words spoken in a day by all male and all female students at this university?

Short Answer

Expert verified

There is no convincing evidence of a difference in the average number of words spoken in a day by all male and all female students at this university.

Step by step solution

01

Given information

Given that,

x¯1=16569x¯2=16177n1=56n2=56s1=9108s2=7520α=0.05

The given claim is that there is a disparity in means.

02

Calculation

Now we must determine the most appropriate hypotheses for a significance test.

As a result, either the null hypothesis or the alternative hypothesis is the claim. According to the null hypothesis, the population proportions are equal. If the claim is the null hypothesis, the alternative hypothesis is the polar opposite of the null hypothesis.

The appropriate hypotheses for this are:

H0:μ1=μ2Ha:μ1notequaltoμ2

Where we have,

μ1is the true daily average number of words spoken by all male students at this university.

μ2is the true average number of words spoken by all female students at this university on a given day.

Locate the following test statistics:

=16569-16177-09108256+7520256=0.248

The degree of liberty will now be:

df=min(n1-1,n2-1)=min(56-1,56-1)=55

Since the student's T distribution table in the appendix does not contain the value of df=55so we will take the nearest value df=50So the P-value will be:
P>2(0.25)=0.50

On the other hand using the calculator command: 2×tcdf(0.248,1E99,55)which results in the P-values as 0.80506
And we know that the null hypothesis is rejected if the P-value is less than or equal to the significance level.

P>0.05Fail to RejectH0

Therefore, We conclude that there is no convincing evidence that the average number of words spoken per day by all male and female students at this university differs.

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Most popular questions from this chapter

You can find some interesting polls online. Anyone can become part of the sample just by clicking on a response. One such poll asked, “Do you prefer watching first-run movies at a movie theater, or waiting until they are available to watch at home or on a digital device?” In all, 8896people responded, with only 12%(1118people) saying they preferred theaters. You can conclude that

a. American adults strongly prefer watching movies at home or on their digital devices.

b. the high nonresponse rate prevents us from drawing a conclusion.

c. the sample is too small to draw any conclusion.

d. the poll uses voluntary response, so the results tell us little about all American adults.

e. American adults strongly prefer seeing movies at a movie theater.

Music and memory Refer to Exercise 87.

a. Construct and interpret a 99%confidence interval for the true mean difference. If you already defined the parameter and checked conditions in Exercise87, you don’t need to do them again here.

b. Explain how the confidence interval provides more information than the test in Exercise .

Based on the P-value in Exercise 71, which of the following must be true?

a. A 90%confidence interval for μM−μF3051526=0.200=20.0%μM-μFwill contain 0

b. A 95%confidence interval for μM−μF3051526=0.200=20.0%μM-μFwill contain 0

c. A 99%confidence interval for μM−μF3051526=0.200=20.0%μM-μFwill contain 0

d. A 99.9% confidence interval for μM−μF3051526=0.200=20.0%μM-μF will contain 0

Quit smoking Nicotine patches are often used to help smokers quit. Does giving medicine to fight depression help? A randomized double-blind experiment assigned 244smokers to receive nicotine patches and another 245to receive both a patch and the antidepressant drug bupropion. After a year, 40subjects in the nicotine patch group had abstained from smoking, as had 87in the patch-plus-drug group. Construct and interpret a 99%confidence interval for the difference in the true proportion of smokers like these who would abstain when using bupropion and a nicotine patch and the proportion who would abstain when using only a patch.

Friday the 13th Do people behave differently on Friday the13th? Researchers collected data on the number of shoppers at a random sample of 45grocery stores on Friday the 6thand Friday the 13thin the same month. Then they calculated the difference (subtracting in the order6thminus13th ) in the number of shoppers at each store on these 2days. The mean difference is -46.5and the standard deviation of the differences is 178.0.

a. If the result of this study is statistically significant, can you conclude that the difference in shopping behavior is due to the effect of Friday the 13thon people’s behavior? Why or why not?

b. Do these data provide convincing evidence at theα=0.05level that the number of shoppers at grocery stores on these 2days differs, on average?

c. Based on your conclusion in part (a), which type of error—a Type I error or a Type II error—could you have made? Explain your answer.

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