Download HW#1 - Classes

5 April 2017
To: CBEE 213 Class
From: Professor Koretsky
Subject: Homework #1
_____________________________________________________________________________
Below is the first homework assignment of the quarter. This assignment is due 12 April 2016 in
studio. Please conform to the format described on the class web site.
http://classes.engr.oregonstate.edu/cbee/spring2017/cbee213-010/HWFormat.pdf If you have
any questions, feel free to see me or one of the other instructors during office hours or by
appointment.
Context
In 1970, Congress instituted a random selection process for the military draft. All 366 possible
birth dates were placed in plastic capsules in a rotating drum and were selected one by one. The
first date drawn from the drum received draft number one and eligible men born on that date
were drafted first. The Draft Number represents which position a given birth date is drafted.
The data set shows Draft Number for each day of the calendar year. Perform the following
statistical analysis:
We will analyze the data using 3 different computer tools
Excel
1. For the month of January find the mean draft number as follows:
A. Find the mean draft number using the function
x
“=Average(1st cell:last cell)” = _________________
From Format choose “cells / number / decimal places 1” or execute with menu
button. Use appropriate significant figures for the remainder of the worksheet.
B. Find the standard deviation of the draft number using the function
s
“=STDEV(1st cell:last cell)”
= _________________
3. Repeat for each month and format appropriately; it may be useful to cut and paste. Make a
summary table of Month, Mean draft number, Std. dev. draft number.
4. For the January and December data only: find the median, first quartile, third quartile,
maximum and minimum, and format appropriately: Commands are as follows:
“=Median(1st cell:last cell)”
x˜ Jan =______________________
x˜ Dec = ______________________
“=quartile(1st cell:last cell, 1)”
Q1,Jan =______________________
Q1,Dec =______________________
“=quartile(1st cell:last cell, 3)”
Q3,Jan =______________________
Q3,Dec =______________________
“=Max(1st cell:last cell)”
x Jan =______________________
x Dec = ______________________
“=Min(1st cell:last cell)”
x Jan =______________________
x Dec = ______________________
4. Sketch a Box plot for Months January and December by hand. Are the distributions
symmetric? Do the data make physical sense?
5. Make the following scatter plots
A. Plot all the individual Draft No vs. month. Can you see any trends?
B. Plot the average Draft No vs. month and standard deviation vs. month. Can you see any
trends?
6. Click the “office button”, choose “Excel Options” under the “Add-Ins” menu choose
Analysis ToolPak. Press Go, check Analysis ToolPak, click OK. Under the Data menu open
“Data Analysis” and choose “Descriptive Statistics”.
For input range highlight “January Draft Number” data. For output choose “output range” on
same sheet. Check summary statistics. What values have you already calculated?
StatGraphics
1. For StatGraphics, like most statistical software packages, data needs to be in a particular
form, where all the data associated with a particular variable is in the same column.
2. Open StatGraphics from the Programs/COE Apps (at least on the Gleeson computers) menu.
Choose Open Data Source / External Data file
Choose in a plain text or spreadsheet file and open the original .xls file (the file you have
modified will not work).
Choose read excel variable names from first row
Note how the data are formatted.
3. For StatGraphics Classic … Describe/ numeric data/ subset analysis...select “Draft No” for
data box, and “Month No” codes. Click OK.
(For StatGraphics Centurian… Analyze/Variable Data/Multisample Comparision/subset
analysis) Choose Tabular options (box in yellow, second from the left) and perform summary
stats.
Next, use right hand mouse and click Pane options and compare to Excel values.
4. Identify the box plots. How do the January and December data compare to your box plot by
hand?
Matlab
Make a boxplot of all the data
• You can use Import Data to create a script that imports the raw data
• You can use the command boxplot(DraftNo,MonthNo) to create a boxplot
Analysis and Conclusion:
Analyze the data. What do you think is the most significant conclusion you can draw? Support
your statement with data. What data led you to this conclusion? What do you think is the
cause?
Turn in your Excel, StateGraphics, and MATLAB files on teach as well as this written
worksheet.