Does reintroducing wolves into an ecosystem improve the overall health of the system (as measured by species richness)? A team of ecologists tested this on 30 different forested parks. Assume the researchers performed an experiment and calculated a p-value of 0.019.  Complete the statements below: Using a significance level of 0.05, the researchers should the null hypothesis. It is possible that they have committed a type error.

A researcher wants to answer the question: Do used Subaru Foresters cost more in Washington State than they do in Tennessee, on the average?  The researcher randomly chooses 20 used Foresters for sale in Washington State and randomly chooses 20 used Foresters for sale in Tennessee. The asking price (in thousands of dollars) and state are recorded for each car. The researcher used the data to create the randomization distribution below:   Decide whether each of the statements below is true or false when considering all provided information.

Data was obtained from a randomly selected sample of n = 22 smart watch users.  These smart watch users indicated they stood for an average of 14 minutes per day with a standard deviation of 4 minutes per day. The calculated standard error of the mean is 0.85 minutes per day. Assume that all conditions are met to use the theoretical t distribution for inference. Which is the correct 99% confidence interval for the average minutes per day stood by Smart-watch users?  

Two researchers perform two different hypothesis tests.   Researcher A obtained a p-value of 0.03. Researcher B obtained a p-value of 0.15 Based on this information, the p-value from researcher gives stronger evidence against the null and in favor of the alternative.  Using a significance level of 0.05, researcher A should the null and researcher B should the null.

A large intro class did a bead box activity to estimate the proportion of blue beads in a very large box of beads.  2000 students took random samples of size 100 and recorded their sample proportions.   A dotplot of these 2000 proportions is found below.  Your sample proportion was 0.50. Based on the sampling distribution found above, which of the below options is closest to the true population proportion of blue beads in the box?

Netflix claims that 50% of U.S. households now have a subscription. We want to find evidence that the true percentage is different. A survey of n = 472 randomly chosen U.S. households finds that the proportion who have a subscription to Netflix is 46%. The correct null and alternative hypotheses for this situation would be: Ho: Ha: Assuming the relevant p-value for this test was 0.002, complete the conclusion below: We the null hypothesis.  We convincing evidence that the proportion of U.S. households with a subscription to Netflix is different than 0.50.

Consider the average price of doughnuts from 200 bakeries in the United States. For the population of interest, a 95% confidence interval for the average price per doughnut is $1.70 plus or minus 0.45 cents.  For this example, match the numbers below to the correct statistical terms:

We have access to the complete dataset of all ages (in years) at death for First Ladies of the U.S. who have passed. From this data set we know that the average age at death is 71.7 years. You are interested in how the sample statistics vary for different samples of size n=15 from this population.   A sampling distribution is constructed where one of the samples is used to create a bootstrap distribution.    This sample has mean: x-bar = 78 years. Below are boxplots of the sample of size n = 15, the sampling distribution, and the bootstrap distribution (although not necessarily in that order!).  Use all of the provided information to select the correct reason for each Boxplot identification. Boxplot A is the sample of n = 15 because it centered at the where the sample standard deviation (s) is the value of the standard error found with the sampling distribution. Boxplot B is the sampling distribution because it is centered at the and has a standard error that is roughly equal to the estimated standard error found with the . Boxplot C is the bootstrap distribution because it is centered at the and has an estimated standard error that is roughly equal to the standard error found with the .

Note: If you have trouble seeing the images, use Ctrl  +  to zoom in and Ctrl – to zoom back out. Use the information in the screenshot to correctly complete the statements below: The correct calculation for the 95% confidence interval is ± .  Based on this bootstrap distribution… 20 a plausible value for the population mean score 33 a plausible value for the population mean score Each dot in the bootstrap distribution represents the of a bootstrap sample drawn replacement from the original . When considering the population mean: .

We are testing the hypotheses: Ho: