A survey of Internet users reported that 20% downloaded music onto their compute

Question

A survey of Internet users reported that 20% downloaded music onto their computers. The ling of a suts by the recording industry may be a reason why this ercent has decreased from the estimate of 29% rom a survey taken two years before. Assume that the sample sizes are both 136. Using a significance test, evaluate whether or there as een a change n he percent of Internet users who download music. Provide all details for the test. (Round your value for z to two decimal places. Round your P-value to four decimal places.) P-value- Summarize your conclusion. We conclude that the proportions are not different. O We conclude that the proportions are different. O We conclude that the means are different. 0 we conclude that the means are not different We cannot draw any conclusions using a significance test for this data Also report a 95% confidence interval for the difference in proportions. (Round your answers to four decimal places.) Explain what information is provided in the interval that is not in the significance test results. The interval shows no significant change in music downloads. O The interval does not provide any more information than the significance test would tell us. O The interval gives us an idea of how large the difference is between the first survey and the second survey. O The significance test does not indicate the direction of change, but the interval shows that the music downloads decreased The interval tells us there was a significant change in music downloads, but the test statistic is inconclusive

Explanation / Answer

The statistical software output for this problem is:

Two sample proportion summary hypothesis test:
p1 : proportion of successes for population 1
p2 : proportion of successes for population 2
p1 - p2 : Difference in proportions
H0 : p1 - p2 = 0
HA : p1 - p2 0

Hypothesis test results:

95% confidence interval results:

Hence,

z = -5.46

p - Value = 0.0000

We conclude that proportions are different.

95% confidence interval: (-0.1221, -0.0579)

Option C is correct.

Difference Count1 Total1 Count2 Total2 Sample Diff. Std. Err. Z-Stat P-value p1 - p2 272.2 1361 394.69 1361 -0.09 0.016487031 -5.4588361 <0.0001

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