Statistics 101L – Laboratory 2
For today's lab, you will collect more data, this time on variables that may be related. We will also
look more closely at the distribution of data using the statistical package JMP.
Activity 1:
Statistics is about variation. Your group will be doing basic research in morphology, the study of
form and structure in plants and animals. You are going to measure your height and your left and
right hand spans, the distance between the tip of your little finger and the tip of your thumb. To
measure your height you must remove your shoes. Stand with your back straight against the wall
and look straight ahead. Have a member of your group place a yard/meter stick flat on your head.
Make a small pencil mark on the wall (be sure to erase these afterwards). Measure the height in
centimeters. To measure your right hand span, put your hand on a ruler. Stretch your hand and
measure the distance, again in centimeters, between the tip of your thumb and the tip of your little
finger. Repeat this procedure with your left hand. Record your name, gender, height and hand
spans on your answer sheet.
Activity 2:
In this activity, we will look at the distribution of colors of M&Ms and see if the different lab
groups got different color distributions. This will be done using the statistical analysis package
JMP. Follow the directions in the Guide to Using JMP in Stat 101 to open the data set
M&M_Colors.JMP from the course web page (www.public.iastate.edu/~wrstephe/stat101L.html).
Use Graph – Chart to create a Pie Chart and Bar Chart for the distribution of colors. You have to
include the Color Freq as a Statistic for the % of Total in order to get the right proportions. You
can right click on the colors in the Legend and change the colors to get a more appropriate display.
Print off a copy of the output and turn it in with your lab. Use the output to answer the questions
on the lab answer sheet.
Activity 3:
In this activity, we will look at the distribution of the Total Weight of Fun Size Bags of M&Ms
using the data collected in Lab 1 last week. Open the data set M&M_S08.JMP from the course
web page (www.public.iastate.edu/~wrstephe/stat101L.html). Use JMP to analyze the data on the
Total Weight of bags. General instructions are given in the Guide to Using JMP in Stat 101.
Include a stem and leaf plot for the distribution of Total Weight. Print off a copy of the output and
turn in with your lab. Use the output to answer the questions on the lab answer sheet.
Note: For the distribution of the Total Weight, JMP does not create a histogram that looks like the
ones we have seen in class. To get a more conventional histogram, choose a Horizontal Display
under Display Options (or Stack the Distribution). Go to the Hand Tool (grabber) from the tool bar
at the top of the main window. Place the Hand Tool on the tallest bar and drag towards the
horizontal axis until the bars fill up the unit intervals. Slide the entire histogram so that the bars are
centered on the integer values on the horizontal scale. Don’t forget to include a vertical axis label.
Data Collection Sheet
Name
Gender Height (cm)
Right Hand Span (cm)
Left Hand Span (cm)
Questions for Activity 2:
a) Looking only at the Pie chart;
• Which color has the highest percentage? What is that percentage?
•
Which color has the lowest percentage? What is that percentage?
b) Looking only at the Bar chart;
• Which color has the highest percentage? What is that percentage?
•
Which color has the lowest percentage? What is that percentage?
c) Which display, Pie chart of Bar chart gives a more informative graphical display of the
distribution of colors in Fun Size Bags of M&Ms? Explain briefly.
Questions for Activity 3:
a) Looking at the histogram, describe the distribution of the total weight of the sample of 88
Fun Size Bags of M&Ms.
b) Does JMP use a split stem for the stem plot? How do you know?
c) Give the values of the sample mean and sample median for the Total Weight of Fun Size
Bags of M&Ms. Describe in words what each value is summarizing about the center of the
distribution of Total Weight.
d) The Fun Size Bags are not labeled for individual sale, and so, do not include a label weight.
Based on the distribution of the Total Weight, how would you label Fun Size Bags for
individual sale? Explain your reasoning.