Research Methods Appendix – Introduction to SDA

Author:   Ed Nelson
Department of Sociology M/S SS97
California State University, Fresno
Fresno, CA 93740
Email:  ednelson@csufresno.edu

Notes to the Instructor:  This is an appendix to the series of 13 exercises that were written for an introductory research methods class.  The purpose of this appendix is to provide an introduction to SDA (Survey Documentation and Analysis).  SDA is an online statistical package written by the Survey Methods Program at UC Berkeley and is available without cost wherever one has an internet connection.  The first exercise in this series focuses on the research design which is your plan of action that explains how you will try to answer your research questions.  Exercises two through four focus on sampling, measurement, and data collection.  The fifth exercise discusses hypotheses and hypothesis testing.  The last eight exercises focus on data analysis.  In these exercises we’re going to analyze data from one of the Monitoring the Future Surveys (i.e., the 2015 survey of high school seniors in the United States).  This data set is part of the collection at the Inter-university Consortium for Political and Social Research at the University of Michigan.  The data are freely available to the public and you do not have to be a member of the Consortium to use the data.  A weight variable is automatically applied to the data set so it better represents the population from which the sample was selected.  You have permission to use this exercise and to revise it to fit your needs.  Please send a copy of any revision to the author so I can see how people are using the exercises. Included with this exercise (as separate files) are more detailed notes to the instructors and the exercise itself.  Please contact the author for additional information.

I’m attaching the following file.

·         This page in MS Word (.docx) format.
 

Part I – Opening the Data Set

In these exercises we’re going to use the Monitoring the Future (MTF) Surveys of high school seniors in the United States that have been conducted yearly since 1975.  There is a website that will give you a lot of information about this study.  Here’s a brief description from the website’s home page.

“Monitoring the Future is an ongoing study of the behaviors, attitudes, and values of American secondary school students, college students, and young adults. Each year, a total of approximately 50,000 8th, 10th and 12th grade students are surveyed (12th graders since 1975, and 8th and 10th graders since 1991). In addition, annual follow-up questionnaires are mailed to a sample of each graduating class for a number of years after their initial participation.”

Information about these surveys is archived at the Inter-university Consortium for Political and Social Research (ICPSR) located at the University of Michigan.  Start by going to their website.  In the upper-right corner of the home page click on “Log In/Create Account.”  Scroll down and click on “Create Account” below “New User.”  Fill in the requested information and click on “Submit.”  It will create your account and give you access to the ICPSR archive.  You can use your account from anywhere you have internet access.  If you don’t use your account for six months, your account will go away.  All accounts are free.

If you are a student, faculty member or staff at a university or college that belongs to the ICPSR, you will have access to all the archive’s data holdings.  If you are not, then you will only have access to public-use data.  Fortunately, the MNF Surveys were funded for public access so you have access to this study regardless of your status.

Once you have created your account, click on “Find Data” in the menu bar at the top of the screen.  Then type “Monitoring the Future” in the “Find Data” box.  Look through the search results for the following.  It will likely be one of the first search outcomes.

Monitoring the Future: A Continuing Study of the Lifestyles and Values of Youth, 1994 (ICPSR 6517) Bachman, Jerald G.; Johnston, Lloyd D.; O'Malley, Patrick M. 
*    63 more results in Monitoring the Future (MTF) Series

Click on the link in the lower right for "Monitoring the Future (MTF) Series.”  Scroll down a little ways until you see “Most Recent Studies” and click on the one that says “Monitoring the Future: A Continuing Study of American Youth (12th-Grade Survey), 2015.”  That’s the survey that we will be using in these exercises. 

Under “Dataset(s)” you will see a listing for “DS1:  Core Data.”  You’ll notice that there is an option for “Analyze Online.”  We’re going to use SDA (Survey Documentation and Analysis) to analyze the data which is an online statistical package written by the Survey Methods Program at UC Berkeley and is available without cost wherever one has an internet connection.  Click on “SDA” to open the program.  You should see the “Terms of Use” which is a legal agreement you need to agree to use to use the data.  Read it and then click on “I agree.”  You should see Figure 1 on your screen.

 This is the SDA dialog box.
Figure 1
 

Part II – SDA Dialog Box

Figure 1 shows you the SDA dialog box which is your interface to SDA.  Let’s spend a little time exploring the dialog box.

  • In the very top line is the name of the data set you opened.  Always check to make sure you opened the correct data set.  It should say that you have opened the Monitoring the Future 12th- Grade Survey, 2015, Core Data.
  • Below that you will see five buttons – Analysis, Create Variables, Download, Codebook, and Getting Started.
    • Getting started is an introduction to SDA but it has way more information than you need.  We’ll refer to it at times in later exercises.
    • Codebook has important information that you will nee
      • Variable List – Click on “Standard Variable List” and you will see a list of all the variables in the core data set.  The variables are grouped in categories including the following.
        • Demographic variables describing both the respondent and the respondent’s family
        • Educational and military aspirations
        • Political, religious, and school attitudes and beliefs
        • Employment and income
        • Recreational information
        • Driving record
        • Drug use
      • SDA Codebook
        • How you should cite the study in your paper
        • Information about the research design
    • Download which tells you how to download the data.  You don’t need to worry about this since we won’t be downloading the data.
    • Create Variables which explains how to recode variables. Instructions for recoding are included in these exercises.
    • Analysis which is what you will be using most of the time.  Pointing your mouse at “Analysis” shows you the various statistical techniques that SDA will carry out for you.  Point to the technique that you want to use and click on it.  We’ll be using some of these techniques but not all.
       

Part III – Carrying Out the Statistical Analysis

We’re going to use frequencies as an example of how to run one of these statistical techniques.  Point your mouse at “Analysis” and click on “Run Frequencies or Crosstabulation.”   Your screen should look like Figure 1.

Notice that there is a mini-code on the left-side of the screen.  What you see is the categories of variables in the core data set.  These include categories such as demographics, aspirations, and substance abuse.  Click on the “+” sign to the left of one of the categories, for example, “Substance Abuse”.  This will expand the codebook and show you all the subcategories of this category.  Your screen should look like Figure 2. 

 This is the mini-codebook for the substance abuse variables.
Figure 2

  The second subcategory is “Alcohol.”  Click on the “+” sign to the left of Alcohol.  Your screen should look like Figure 3.

 This is the mini-codebook for the alcohol variables.

Figure 3

The variable names are on the far left, for example, V2103.  To the right of the variable name is the variable label.  Click on V2013.  The variable now appears in the “Variable Selection” box at the top of the screen.  Your screen should look like Figure 4.

 This is the variable selection box.
Figure 4

Click on the “View” button to the right of the variable name and you will see the wording of question, the frequency distribution, and the values that have been designated as missing values.  Now click on “Row” to the right of “Copy to” and the variable name will be entered in the “Row” box.  Your screen should look like Figure 5.  You could also have typed V2103 in the box.  Either way works.

 This is part of the SDA dialog box for "Analysis" with V2103 filled in the "Row" box.
Figure 5

Click on “Run the Table” at the bottom of the page to get the frequency distribution for V2103.  Your screen should look like Figure 6.

 This is the SDA output showing the frequency distribution for V2103.
Figure 6

The table shows that about 65% of high school seniors said they had an alcoholic drink while 35% said they didn’t.

You can copy and paste the tables from the SDA output into your paper.  Or you could create a screen capture using an application like Snipping Tool.