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Data Use Tutorial

Are you interested in determining the average age at which men versus women begin smoking? What if you need to know whether age at marriage differs between your region of the country and other regions, or about differences in political attitudes based on age, gender, education, race, or ethnicity? These and countless other questions can be answered by studies in the ICPSR data holdings.

Please note that ICPSR does not provide publications, reports, or ready-made statistics. What we do supply are the numeric raw data used to create publications, reports, and figures. To view findings that others have published, select the "related literature" link for a given data set on the search results page or at the top of each study description. This will take you to a bibliography of publications based on that data, with links to online reports, when available.

Let's Get Started...

Overview

To begin a project involving data analysis, you will first need to search for a dataset to answer your research questions. Then you can download the dataset and run a simple statistical procedure(*) on your own computer with your own software, or you can use the online data analysis system for a selection of the ICPSR datasets available on our site.

* You will need basic statistical skills for using the online analysis system and more advanced skills for running your own analysis, although SAS, SPSS, and Stata setup files are provided with many ICPSR datasets.

While the ICPSR holdings include several time series and other types of aggregate data, our holdings consist mainly of raw data derived from surveys, censuses, and administrative records. These data were originally collected for specific research or administrative purposes. However, the data have research potential that outlives the original purposes for which they were collected. ICPSR preserves these valuable data resources and makes them publicly available for secondary analysis.

The ICPSR data holdings cover a wide range of social science areas such as population, economics, education, health, social and political behavior, social and political attitudes, history, crime, aging, and substance abuse.

Terms, formats, and statistical vocabulary

Before you begin working with ICPSR data, we suggest that you familiarize yourself with the methodological terms that are widely used across this Web site. If you need help with social science terminology, or with basic computing concepts, we do strongly suggest that you consult the following sources:

Searching and finding the data you need

If you already have information about the dataset you need -- for example, a specific title of a survey (Consumer Expenditure Survey, 1999: Diary Survey) or the name of the principal investigator (United States Department of Labor, Bureau of Labor Statistics), then you may use the Search function on the ICPSR front page or on the Data page to locate it. (The Basic Search function allows more searching options.) However, if you do not have a reference or if you prefer to explore the available data in a given area, it is wise to start by browsing the ICPSR data collection by subject. If you are unable to find a subject heading that describes the focus of your search, you may wish to consult the ICPSR Thesaurus, which provides a broader list of social science subject terms.

If your searches are returning too many or too few results, we strongly encourage you to read over our Frequently Asked Questions About Searching page, which will explain how to do refined searching.

Search results appear as a list of datasets and/or documents. Studies that include downloadable data will have a "description" and a "download" link. (You may also see entries for CD-ROMs, series descriptions, and other pages on the ICPSR Web site.)

Example 2: Search Results Screen

screenshot of the search results page

The "description" link takes you to the corresponding study description (example of ICPSR 3227), which gives a useful summary of the data contents, scope, time period, and other details that will help you to determine the relevance of a dataset for your research.

The "download" link takes you to a page that lists data and documentation files available for download. (This is described further below.)

The "related literature" link will return a list of bibliographic citations for publications based upon the data.

The "online analysis" link is only present for studies that have online analysis components, and will either take you directly to the online analysis screen, or will list the online analysis components related to that particular study.

Once you have chosen to go on with a dataset, you may proceed to the Accessing data instructions.

Accessing data

Data access procedures differ according to the type of data being downloaded and whether the user is affiliated with an ICPSR member institution. Note, however, that all ICPSR technical documentation is freely available to all users.

Data in the special topic archives

The majority of the data in the ICPSR archive were acquired and processed through support of the ICPSR membership and are downloadable only by individuals at ICPSR member institutions. The remaining data are made available through the topical archives, which are federally funded. Thus, these data are freely available to the general public. Documentation files are freely available, regardless of how the archiving of the study was funded. If data files are not freely available, then "Documentation Only" will be the only selectable option on the download page.

Is your school an ICPSR member institution?

You can find out by looking at our list of member institutions. If your school is not a member, you may still obtain data for an access fee by contacting ICPSR's User Support unit at netmail@icpsr.umich.edu.

ICPSR Direct

If you are at a member school, your school is most likely participating in the ICPSR Direct program. ICPSR Direct is a service providing direct access to the ICPSR data holdings for all students, faculty, and staff at ICPSR member institutions. If your institution is a member but has not yet joined the ICPSR Direct service, please contact your Official Representative (OR) whose name and email address can be obtained from the ICPSR member list. Your OR can either provide the data for you directly, or arrange for your institution to sign up for ICPSR Direct.

MyData

If you are a first-time user of ICPSR Direct, we will ask you to create a MyData account. Logging in with your MyData account and agreeing to the Terms of Use authorizes you to download data files from that point on. On subsequent visits to the site, when you begin to download a dataset, you will be asked to enter your email address and MyData password.

Restricted Data

Some datasets have additional restrictions due to the sensitive nature of the data. In such cases, ICPSR will require the user to complete and sign a Restricted Data Use Agreement in order to obtain access to the data for a specific time period. If the study you wish to download is restricted, you will want to read over our procedures for accessing restricted data.

Downloading

The Download screen (example of ICPSR 8475) walks you through a series of steps to download the files you need. Step 1 lists the available data formats, while Step 2 lists the datasets in the study. Make your choices, and then use the button in Step 3 to add the files to your Data Cart. You may use Step 4 to review the contents of your cart, or simply click on the button in Step 5 to download a zipped folder that contains all your files.

If you're uncertain whether this study fits your needs, it is a good idea to first browse the codebook or other documentation files, which can be accessed by clicking on the Browse Documentation tab.

Example 3: Download Screen

screenshot of the download page

Note that in downloading data from ICPSR, you signify that you agree not to share the data with anyone not authorized by ICPSR to receive it. You further agree to the terms of use.

Viewing the description file is also a good practice when preparing to download data. The description file contains a general description of the study, and sometimes supplies important information about file formats and other unique characteristics of the data.

Analyzing data using statistical software

As we have mentioned above, statistical software is necessary to define, manipulate, and extract variables and cases within data files. Furthermore, interpretation and analysis of the data require at least basic statistical skills and preferably some knowledge of a statistical software package. Students of the social sciences usually acquire this knowledge during their first two years in college.

Setup files, which allow the user to read data files into statistical software packages, accompany the majority of the ICPSR studies. ICPSR currently provides setup files for SAS, SPSS, and Stata, three of the more commonly used analytical software packages for the social sciences.

SAS, SPSS, and Stata setup files and portable files can be used either with the procedural version of these packages or with their Windows counterparts. The following instructions explain the different components of SAS, SPSS, and Stata setup files. Setup files for certain collections may not contain all of the commands listed below.

Small data files may also be analyzed within spreadsheet software such as Excel. In Excel, open the data file as a txt file, and use the "Text Import Wizard" to define variables and incorporate them into the spreadsheet. You will then need to copy variable labels from the codebook or from the setup files into the column headings. To summarize and analyze the data, click "Tools" => "Data Analysis" and then select the suitable statistical procedure from the menu.

Online data analysis using SDA

Online data analysis enables users to explore datasets using certain statistical procedures without downloading data and setup files, and without being familiar with any statistical packages. ICPSR currently offers online analysis components for selected data collections using two data analysis systems: Survey Documentation Analysis (SDA), and Nesstar.

Brief overview of the SDA online data analysis system

The "Getting Started" button on the right side of the SDA menu bar offers helpful instructions on the following topics: Adjusting Your Browser, Program Selection, Variable Selection, Running the Program.

Version 3.3 offers users a number of capabilities:

  • Browse the codebook for a dataset
  • Select variables, analysis programs, and program options from a single browser window
  • Perform certain statistical procedures, such as:
    • List values of individual cases
    • Frequencies
    • Crosstabulations
    • Comparisons of means
    • Correlation matrix
    • Ordinary Least Squares (OLS) regression
  • Create bar, line, and pie charts for frequencies and crosstabulations
  • Manipulate variables
    • Recode variables
    • Compute new variables
    • List newly created variables
  • Create customized subsets of selected variables and cases
    • Now includes user-created variables from the Recode and Compute programs
  • Download the subset, including:
    • ASCII data file with optional delimiters
    • SAS, SPSS, or Stata setup files
    • Codebook customized for the selected subset

Accessing SDA data collections

You may access SDA through selected individual data collections. Click on the Online Analysis link that appears on the Search Results page, the Download page, or the Description page. If you do not see an Online Analysis link on these pages, the study is not available for online analysis.

You may also browse a list of SDA data collections available for online analysis. Only selected ICPSR data collections are available for online analysis. If you find the data collection you need on this list, click on the Online Analysis link and follow the Online Help Files for SDA Users instructions.

The following examples were extracted from the National Survey of Black Americans, Waves 1-4:

Example 1: Customizing a subset of female respondents

See outputs of this session:

Example 2: Comparison of means of satisfaction with police in respondent's neighborhood

See also

Need More Information?

The Survey Documentation and Analysis (SDA) online data analysis system made available by ICPSR was developed and is maintained by the Computer-assisted Survey Methods Program at the University of California, Berkeley.

If you have questions about using SDA and would like to contact ICPSR staff, go to the Help page, which will provide you with contact information for ICPSR staff and for your local ICPSR representative.

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