Exam 8: Inferences From Two Samples

Use the following data for the next questions. Scientists, researching large woody debris (LWD), surveyed the number of LWD pieces from aerial photos taken annually for the past 35 years at two different sites. Over the 35 years of photos examined, the first site had a mean number of LWD pieces per hectare per year (LWD/ha/yr) of 3.7 pieces with a standard deviation of 1.9. The second site had a mean number of LWD/ha/yr of 4.3 with a standard deviation of 2.4. Assume a .05 significance level for testing the claim that the mean LWD/ha at the first site had less than the mean LWD/ha/yr at the second site. Also, assume the two samples are independent simple random samples selected from normally distributed populations. -Use a .05 significance level to find the F test statistic for the claim that the LWD abundance at the first site has a standard deviation different from that at the second site.

Use the following data for the next questions. Scientists, researching large woody debris (LWD), surveyed the number of LWD pieces from aerial photos taken annually for the past 35 years at two different sites. Over the 35 years of photos examined, the first site had a mean number of LWD pieces per hectare per year (LWD/ha/yr) of 3.7 pieces with a standard deviation of 1.9. The second site had a mean number of LWD/ha/yr of 4.3 with a standard deviation of 2.4. Assume a .05 significance level for testing the claim that the mean LWD/ha at the first site had less than the mean LWD/ha/yr at the second site. Also, assume the two samples are independent simple random samples selected from normally distributed populations. -Find the t test statistic.

Determine which samples are independent samples.

Determine which samples are dependent samples.

Use the following sample sizes and numbers of successes for the next questions. Medical researchers studying two therapies for treating patients infected with Hepatitis C found the following data. Assume a .05 significance level for testing the claim that the proportions are not equal. Also, assume the two simple random samples are independent and that the conditions are satisfied. -Find the test statistic.

Use the following data for the next questions. Scientists, researching large woody debris (LWD), surveyed the number of LWD pieces from aerial photos taken annually for the past 35 years at two different sites. Over the 35 years of photos examined, the first site had a mean number of LWD pieces per hectare per year (LWD/ha/yr) of 3.7 pieces with a standard deviation of 1.9. The second site had a mean number of LWD/ha/yr of 4.3 with a standard deviation of 2.4. Assume a .05 significance level for testing the claim that the mean LWD/ha at the first site had less than the mean LWD/ha/yr at the second site. Also, assume the two samples are independent simple random samples selected from normally distributed populations. -Identify the null hypothesis and alternative hypothesis for the claim that the LWD abundance at the first site has a standard deviation different from that at the second site.

Use the following data for the next questions. Scientists, researching large woody debris (LWD), surveyed the number of LWD pieces from aerial photos taken annually for the past 35 years at two different sites. Over the 35 years of photos examined, the first site had a mean number of LWD pieces per hectare per year (LWD/ha/yr) of 3.7 pieces with a standard deviation of 1.9. The second site had a mean number of LWD/ha/yr of 4.3 with a standard deviation of 2.4. Assume a .05 significance level for testing the claim that the mean LWD/ha at the first site had less than the mean LWD/ha/yr at the second site. Also, assume the two samples are independent simple random samples selected from normally distributed populations. -Test the given claim using the traditional or P-value method for hypothesis testing about two means. Do not assume that the population standard deviations are equal. Identify the null hypothesis and alternative hypothesis, state a conclusion about the null hypothesis, and state a final conclusion that addresses the original claim.

Use the following data for the next questions. Biologists, researching the effects of adding limestone sand as buffer for acid rain effects in streams, monitored the pH levels of two streams each month for 36 months. The first stream had a mean pH level of 6.8 with a standard deviation of 2.3. The control stream had a mean pH level of 9.2 with a standard deviation of 1.5. Assume a .05 significance level for testing the claim that the mean pH of the first stream was less (more acidic) than the mean pH of the control stream. Also, assume the two samples are independent simple random samples selected from normally distributed populations. -Find the t test statistic.

Use the following sample sizes and numbers of successes for the next six questions. Medical researchers reviewing the risk of death for elderly patients taking dementia drugs found the following data. Assume a .05 significance level for testing the claim that the proportions are not equal. Also, assume the two simple random samples are independent and that the conditions are satisfied. -Find the odds ratio of the odds for death in the placebo group to the odds for death in the dementia drugs group.

Use the following sample sizes and numbers of successes for the next questions. Medical researchers studying two therapies for treating patients infected with Hepatitis C found the following data. Assume a .05 significance level for testing the claim that the proportions are not equal. Also, assume the two simple random samples are independent and that the conditions are satisfied. -Find the odds ratio of the odds for having Hepatitis C after Therapy 1 to the odds for having Hepatitis C after Therapy 2.

Use the following sample sizes and numbers of successes for the next six questions. Medical researchers reviewing the risk of death for elderly patients taking dementia drugs found the following data. Assume a .05 significance level for testing the claim that the proportions are not equal. Also, assume the two simple random samples are independent and that the conditions are satisfied. -Test the given claim using the traditional or P-value method for hypothesis testing about two proportions. Identify the null hypothesis and alternative hypothesis, state a conclusion about the null hypothesis, and state a final conclusion that addresses the original claim.