MAX 201 Spring 2008
Assignment #6: Charts & Graphs; Modifying Data Due at the beginning of class on March 18
thIntroduction
This assignment introduces the charting and graphing capabilities of SPSS and Excel. It also helps you learn how to modify data values using SPSS. All these skills will be useful to you later in the semester when you are writing your paper and preparing your presentation of your research results. [Note about missing values: normally you do NOT want to present “NA”, “NO ANSWER” or “DK”s (Don’t Know). Make sure that you are consistent, so that your SPSS and Excel charts contain the same categories.]
Excel Charts & Graphs
Excel has extensive graphic capabilities, which can help you make strong visual presentations of data. You need to give the proper instructions to the Chart Wizard in order for the charts or graphs to contain the appropriate data.
Making a Pie Chart of PADEG
Open the GSS 2006.xls file you saved on your H drive in Assignment 5.
On a new worksheet in GSS 2006.xls, create a univariate pivot table showing the numerical distribution (“counts”) of PADEG, the same way that you did in Assignment 5.
Name the new worksheet Assign6.
Note: Remember to save frequently! The GSS 2006.xls file is already about 7 megabytes, which is large enough to increase the chances that Excel will crash. You can prevent a lot of frustration and extra work by saving frequently.
To make a pie chart, follow the above directions and:
o Create a pivot table
o Hide missing values (including “Don’t Know”, “Not Applicable”, and “No Answer”) o Supply value labels for the data consistent with the codebook
Select the data and value labels (not the column headings or the grand total), copy and paste special on the same worksheet. Click on the arrow beneath the Paste button on the Home tab and select Paste Special. Choose “Values and number formats” under Paste, and “None”
under Operations).
To activate the Chart Wizard, highlight the data just pasted and click on the Insert tab and select Pie chart (the icon is a circle with blue, yellow, and red slices). Click on “Pie in 3-D.”
Your pie chart should look like the chart for marital status below:
Example: Pie Chart of MARITAL
Count of marital
marital Total
Married 2170 Married 2170
Widowed 366 Widowed 366
Divorced 732 Divorced 732
Separated 156 Separated 156
Never Married 1080 Never Married 1080 Grand Total 4504
To format your chart:
o Click on the Layout tab.
o Under Labels, click on Chart title\Above Chart. Double click where it says “Chart title” and add your own informative title.
o Under Legend, select “Show Legend at Right”
o Under Data Labels, select “More Data Label Options” and make sure that
“Percentage” and “Show Leader Lines” are checked
Place the pie chart as an object in sheet Assign6, where your pivot table and pasted data is.
You may have to move and resize the chart so that it is readable. You can play around with the format for the title and data labels by right clicking on whatever you want to re-format.
Insert your name, assignment, and lab information at the top of the page. Preview the page
before printing to be sure your name, the pivot table, the pasted data, and the chart all fit on
one page.
Making Charts in SPSS; Modifying Data Values
Before issuing commands to SPSS that will analyze data, it is sometimes desirable to modify data values – that is, to combine values of the variable for presentation (note that this can be done in Excel also, but it is more complicated). This is a matter for the analyst’s judgment – for example if there are only a few cases in one category, it may make sense to combine those cases with those taking on the next value. Pay attention to the question and responses, too – you may decide it makes sense to combine the responses “strongly agree” and “agree,” for example. See the example below.
Example: HOMPOP
In this example, we want to make a pie chart of the variable HOMPOP, which is the number of household members. The original frequency table appears below.
A pie chart with too many pieces (i.e., more than 6 or 7) is difficult to interpret, so we want to combine some categories so that the chart will be more visually appealing and easier to read.
We notice that very few people live in households with six or more members. (Categories 6, 7, 8, 9, 10 & 11 all have relatively small values, compared to the values for 1 through 5.)
Therefore, we will combine categories 6 through 11 into one group, creating a new variable, HOMPOP2. Frequencies for this are shown in the table below, “Recoded household size.”
Details of how to do this data transformation are in the next section.
NUMBER OF PERSONS IN HOUSEHOLD
1220 27.1 27.1 27.1
1563 34.7 34.7 61.7
716 15.9 15.9 77.6
590 13.1 13.1 90.7
267 5.9 5.9 96.6
100 2.2 2.2 98.8
37 .8 .8 99.6
11 .2 .2 99.9
3 .1 .1 99.9
2 .0 .0 100.0
1 .0 .0 100.0
4510 100.0 100.0
1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 Total Valid
Frequency Percent Valid Percent
Cumulative Percent
Recoded Household Size
Frequency Percent Valid Percent
Cumulative Percent
Making a bar chart of BYPHONE in SPSS
Similarly, you will modify or “recode” the variable TVHOURS and then make a chart of the frequencies of the values of this variable.
Open the GSS analysis SPSS file you created on your H drive in Assignment 5.
Create a Frequency table showing the numerical distribution (“counts”) and percentages of TVHOURS.
Print the output and close it without saving.
Since simpler is better when presenting data visually, you will want to group the categories.
Use the above example (HOMPOP) as a guide for understanding grouping of categories in your distribution of TVHOURS.
Decide which categories you want to combine for TVHOURS.
Recode TVHOURS to TVHOURS2 by using the “Transform>Recode” commands.
This will produce a “Recode into Different Variables” dialog box. Select TVHOURS and name the “Output variable” TVHOURS2. Click Change. Then click Old and New Values.
In the “Old and New Values” dialog box, you must deal with each of the values (or value ranges) of the original variable and assign these to different (or the same) values for the new variable. Ranges mean that you could specify, for example, that values 6 through 10 in the old variable be assigned the value of “6” in the new variable.
Be careful when you recode to include all the categories that you want in your new variable.
For example if you want category 1 to be the same in both TVHOURS and TVHOURS2 you have to include it in the recode instructions. Any category you do not include, SPSS will assume is missing.
Substitute informative labels for the numerical codes associated with the categories of TVHOURS. Go to View – Variables and click on the bottom right-hand corner of the
“Values” cell for TVHOURS2 (which will be at the end of the data list). Provide a label for each value.
Run the frequency command on the variable TVHOURS2 and choose the chart option (by clicking Charts at the bottom, which takes you to the chart dialog). Choose Bar chart, and Percentages. [Note: this will give you the table and the chart. You could have gone directly to “graphs” on the toolbar, to produce only the chart.]
Print the output (both the table and the chart).
SPSS Charts Showing Relationships between Two Variables
So far, we’ve made charts showing the distribution of a single variable. Charts are also useful to show how two variables are related to one another (basically a visual presentation of crosstab tables).
In SPSS, construct a crosstab table showing the relationship between FEPRESCH and SEX.
Click Cells and ask for “row percents”.
FEPRESCH is the dependent variable. Put it in the columns, and SEX in the rows.
Open a new Word document, put your name, section, and Assignment 6 at the top, and paste the table into this document.
Produce a “clustered bar chart” showing this relationship. On the menu, choose Graphs>Bar.
In the dialog box choose “clustered” and “summaries for groups of cases.”
Click Define for the “Define Clustered Bar” dialog box. Put FEPRESCH, your dependent variable, in the “category axis” box and your independent variable, SEX in the “define clusters by” box. Bars should represent “% of cases” and not numbers of cases. Under Options be sure that you do not display groups defined by missing values.
Paste the bar chart into your Word document. To copy your chart, double click on your chart in the SPSS output so that the Chart Editor opens. In the “Edit Menu,” select “Copy Chart.”
Then paste your chart into Word.
Finally construct a crosstab table and a bar chart showing the relationship between an
independent nominal or ordinal variable and a dependent nominal or ordinal variable of your choice.
Paste both this second table and the second chart into your Word document, save, and print.
Using Excel to Produce Bivariate Charts
This part of the assignment is just to illustrate how you can produce charts in either SPSS or Excel – this produces a chart for the same two variables used in the section above.
Open a new Excel worksheet.
Type in the relevant percentage information from your second crosstab table above using the independent and dependent variable of your choice that you created in SPSS. Make sure that you are consistent across SPSS and Excel (if you eliminated DKs and NAs in SPSS, also do it in Excel). If I had produced a bivariate table of ABNOMORE and SEX, I would enter the data into an Excel spreadsheet like this:
abnomore
Sex Yes No
Male 45% 55%
Female 40% 60%
Highlight everything except for the dependent variable name (ABNOMORE in this example).
Click on the Insert tab, Charts\Column\2-D Column\Clustered Column to make a column chart. Use the Layout tab to give the chart the appropriate titles and produce it as an object on the same sheet.
Put your name etc. at the top and print the spreadsheet.
To summarize: you should have
1.
An Excel spreadsheet containing your name & section, two tables, and a pie chart of PADEG
2.
