Work using MATLAB:

Create a subfolder specifically for this class in your MATLAB
folder.

Save the data file HW1_Data.xlsx to the
subfolder you created for this class. This file contains homework
and test grades for Sections 1 and 2 from a previous semester.
Names were removed and data were randomized so that student grades
would no longer be in alphabetical order; therefore, student
privacy is protected. You cannot determine which students were in
section 001 and which were in section 002 from this file. Students
who dropped the course have been deleted from the file.

Do the following work in a script file because you will have to
paste your commands below. A few comments in your script file would
be good.

Read the data file into MATLAB. You can do this in a variety of
ways.

Find the measures of central tendency (mean, median, mode) for
HW, Test1 and Test 2. You can do this in a variety of ways,
depending on how you read in the data.

Find the measures of variability (range, variance and standard
deviation) for HW, Test1 and Test 2. You should explore the
differences between sample and population measures of variability.
Do you want to use sample measures of
variability or population measures of
variability? Discuss this with your group members. Then briefly
justify here why you chose to use sample measures (statistics) or
population measures (parameters). (3 points)

Create a variable called Diff which is simply Test2 minus Test1.
Do NOT take the absolute value of the difference.
Find measures of central tendency and measures of variability for
Diff. Compare your answers with your group because there are a few
ways to do this and some of the ways are correct and some are
not!

4.   Fill in the following table with your results.
(6 points)

A normal probability plot is a plot of one’s data on the x axis
versus the normalized scores (called z-scores) of the given data
plotted on the y axis. The y axis is given on a logarithmic scale.
If the graph follows a fairly straight line, we say the data
follows a normal probability distribution. We will discuss normal
distributions in much more detail, but for now, the goal is for you
to learn how to get a normal probability plot easily in MATLAB. If
you want a normal probability plot of a vector V, the MATLAB
command is normplot(V). This is so much easier to produce
in MATLAB than it is in Excel!

Paste normal probability plots for HW and Diff below. Be sure to
distinguish between the plots by editing the title of each plot.
(4 points: 2 points for each plot)

Select a random sample of size 5 from this data. Make sure you
truly randomize your selection. Find the mean and standard
deviation of Test 1 for the sample of size 5.

Select a random sample of size 50 from this data. Again, make
sure you truly randomize your selection. Find the mean and standard
deviation of Test 1 for the sample of size 50.

Which mean is closer to the overall mean? Highlight the mean
that is closer to the overall mean.

A. mean from the sample of size 5

B. mean from the sample of size 50

Compare your results with your group members and with others in
the class. Briefly state the results of your comparisons.
(3 points)