IDEAS home Printed from
MyIDEAS: Log in (now much improved!) to save this paper

Modeling for response variables that are proportions

Listed author(s):
  • Maarten L. Buis


    (Department of Social Research Methodology, Vrije Universiteit Amsterdam)

When dealing with response variables that are proportions, people often use regress. This approach can be problematic since the model can lead to predicted proportions less than zero or more than one and errors that are likely to be heteroskedastic and nonnormally distributed. This talk will discuss three more appropriate methods for proportions as response variables: betafit, dirifit, and glm. betafit is a maximum likelihood estimator using a beta likelihood, dirifit is a maximum likelihood estimator using a Dirichlet likelihood, and glm can be used to create a quasi–maximum likelihood estimator using a binomial likelihood. On an applied level, a difference between dirifit and the others is that the others can handle only one response variable, whereas dirifit can handle multiple response variables. For instance, betafit and glm can model the proportion of city budget spent on the category security (police and fire department), whereas dirifit can simultaneously model the proportions spent on categories security, social policy, infrastructure, and other. Another difference between betafit and glm is that glm can handle a proportion of exactly zero and one, whereas betafit can handle only proportions between zero and one. Special attention will be given on how to fit these models in Stata and on how to interpret the results. This presentation will end with a warning not to use any of these techniques for ecological inference, i.e., using aggregated data to infer about individual units. To use a classic example: In the United States in the 1930s, states with a high proportion of immigrants also had a high literacy rate (in the English language), whereas immigrants were on average less literate than nonimmigrants. Regressing state level literacy rate on state level proportion of immigrants would thus give a completely wrong picture about the relationship between individual immigrant status and literacy.

If you experience problems downloading a file, check if you have the proper application to view it first. In case of further problems read the IDEAS help page. Note that these files are not on the IDEAS site. Please be patient as the files may be large.

File URL:
File Function: presentation slides
Download Restriction: no

Paper provided by Stata Users Group in its series United Kingdom Stata Users' Group Meetings 2006 with number 15.

in new window

Date of creation: 18 Sep 2006
Handle: RePEc:boc:usug06:15
Contact details of provider: Web page:

More information through EDIRC

References listed on IDEAS
Please report citation or reference errors to , or , if you are the registered author of the cited work, log in to your RePEc Author Service profile, click on "citations" and make appropriate adjustments.:

in new window

  1. Papke, Leslie E & Wooldridge, Jeffrey M, 1996. "Econometric Methods for Fractional Response Variables with an Application to 401(K) Plan Participation Rates," Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 11(6), pages 619-632, Nov.-Dec..
Full references (including those not matched with items on IDEAS)

This item is not listed on Wikipedia, on a reading list or among the top items on IDEAS.

When requesting a correction, please mention this item's handle: RePEc:boc:usug06:15. See general information about how to correct material in RePEc.

For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: (Christopher F Baum)

If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.

If references are entirely missing, you can add them using this form.

If the full references list an item that is present in RePEc, but the system did not link to it, you can help with this form.

If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your profile, as there may be some citations waiting for confirmation.

Please note that corrections may take a couple of weeks to filter through the various RePEc services.

This information is provided to you by IDEAS at the Research Division of the Federal Reserve Bank of St. Louis using RePEc data.