Math 224 – Elementary Statistics

STATISTICS – LAB #2

Statistical Concepts

 Using Minitab  Graphics  Shapes of Distributions  Descriptive Statistics  Empirical Rule

Data in Minitab

 MINITAB is a powerful, yet user-friendly, data analysis software package. You can launch MINITAB by finding the icon and double clicking on it or by going to Start > Programs > MINITAB. After a moment you will see two windows, the Session Window in the top half of the screen and the Worksheet or Data Window in the bottom half.

 The survey results from the first lab have already been formatted and entered into a MINITAB Worksheet. You may download the file from my web page or public account; it is saved as ‘Student Survey’. The names of each variable from the survey are in the first row of the Worksheet. All other rows of the MINITAB Worksheet represent a certain students’ answers to the survey questions. Therefore, the rows are called observations and the columns are called variables. Included with this lab, you will find a code sheet that identifies the correspondence between the variable names and the survey questions. Code Sheet

VARIABLE QUESTION NAME Drive Question 1 – How many minutes on average does it take you to drive to UK from your home? State Question 2 – What state (or country if not from United States) were you born? Year Question 3 – What year did you (or expect to) graduate with your bachelor’s degree? Rank Question 4 – Rank all of the courses you are currently taking. The class you look most forward to taking will be ranked one, next two, and so on. What is the rank assigned to this class? Height Question 5 – What is your height to the nearest inch? Shoe Question 6 – What is your shoe size? Sleep Question 7 – How many hours did you sleep last night? Gender Question 8 – What is your gender? Race Question 9 – What is your race? Car Question 10 – What color of car do you drive? TV Question 11 – How many hours (on average) do you spend a day watching TV? Money Question 12 – How much money do you have in your pocket right now? Coin Question 13 – Flip a coin 10 times. How many times did you get tails? Die1 Question 14 – Roll a die 10 times. Record the results. Die2 Die3 Die4 Die5 Die6 Die7 Die8 Die9 Die10 Creating Graphs

 Create a Pie Chart for the variable Car – Pull up Graph > Pie Chart and click in the Categorical variables: box. Now double click on the variable name in the box at the left of the window. Include a title by clicking on the Labels button and typing it in the correct text area (put your name in as the title). Select the Slice Labels tab at the top of the window and check the boxes for Category name, Frequency, and Percent then click OK. Click OK again to create the graph. Now to print the graph – select File > Print Graph.

 Create a Bar Chart for the variable Race – Pull up Graph > Bar Chart and click OK. Set Categorical variables: equal to the corresponding variable using the same procedure as above. Title the graph using Labels (put your name in as the title). Now print the graph.

 Create a histogram for the variable Height – Pull up Graph > Histogram and click OK. Set Graph variables: equal to the corresponding variable. Title the graph (put your name in as the title). Now print the graph.

 Create a stem and leaf plot for the variable Money – Pull up Graph > Stem-and Leaf and set Graph variables: to Money. Enter 10 for the Increment: and click OK. This graph will show up in your Session Window.

Calculating Descriptive Statistics

 Calculate descriptive statistics for the variable Height – Pull up Stat > Basic Statistics > Display Descriptive Statistics and set Variables: to Height. The output will show up in your Session Window.

 Calculate descriptive statistics for the variable Height by Gender – Pull up Stat > Basic Statistics > Display Descriptive Statistics and set Variables: to Height. Also, set By variable: to Gender. The output will show up in your Session Window.

 Select File > Print Session Window to print this information. Make sure to print the stem and leaf plot and the descriptive statistics.

 Select File > Save Current Worksheet As to save the data set. Make sure to keep a copy of this data for future labs. If not you will have to download the file each time you work on a lab assignment. Short Answer

All answers should be complete sentences. You should use the descriptive ‘concepts’ that we have learned in class to answer these questions. The ‘raw data’ should be used only to verify computations. Include copies of all print outs with this assignment. Place completed assignment in your lab portfolio.

1. Create a Pie Chart for the variable Car. Describe your graph. What is the most common color of car for students who participated in this survey?

2. Create a Bar Chart for the variable Race. How diverse is our class in terms of race? Explain your answer.

3. Create a stem and leaf plot for the money variable. Describe the shape and make general summaries.

4. Create a histogram for the heights of students in this class. Describe the shape and make general summaries. Comment on the shape of the distribution; why do you think the histogram for heights of students takes this shape? 5. Produce descriptive statistics for the heights of students overall. Then, produce descriptive statistics for heights of students by gender.

(a) List and compare the 3 means: overall, female, and male. Explain what can be concluded just based on these numbers.

(b) List and compare the 3 medians: overall, female, and male. Explain what can be concluded based on these numbers.

(c) List and compare the 3 standard deviations: overall, female, and male. Explain what can be concluded based on these numbers.

6. Using the empirical rule, (show your calculations) (a) 95% of female heights should be between what two values?

(b) 68% of male heights should be between what two values?