Q. 6.131 - Elementary Statistics

Question

In the special report "Mousetrap: The Most-Visited Shoe and Apparel E-tailers" (Footwear News. Vol. 58. No. 3. p. 18), we found the following data on the average time, in minutes, spent per user per month from January to June of one year for a sample of 15 shoe and apparel retail Web sites.

a. Obtain a normal probability plot of the given data.

b. Use part $\left(a\right)$ to identify any outliers.

c. Use part $\left(a\right)$ to assess the normality of the variable under consideration.

Step-by-Step Solution

Answer

a. As a result, the normal probability curve for the average time spent per user is shown above.

b. As a result, there are no outliers in the normal probability graph.

c. As a result, the average amount of time spent by each user is roughly normal.

Part (a) Step 1: Given Information

Normal probability plot of the given data. The consider average time spent per user.

Part (a) Step 2: Explanation

The normal probability plot of the given data. 

Arrange the given data in ascending order first, then use the table to calculate the normal scores.

Create a normal probability plot, as shown below.

As a result, the normal probability curve for the average time spent per user is shown above.

Part (b) Step 1: Given Information

The outliers in normal probability plot of part$a$.

Part (b) Step 2: Explanation

Take a look at part's normal probability plot.

The information is arranged in a straight line. However, there are no outliers in the plot.

As a result, there are no outliers in the normal probability graph.

Part (c) Step 1: Given Information

The normality of the variable under consideration.

Part (c) Step 2: Explanation

Consider portion a's normal probability plot.

The information is arranged in a straight line.

The variable under examination is a linear variable.

As a result, the average amount of time spent by each user is roughly normal.