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From |
David Hoaglin <dchoaglin@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Regression with multiple age groups |

Date |
Wed, 25 Apr 2012 09:09:33 -0400 |

Dear Shirley, Others will agree that you need to tell the list more about the data and the analysis that you intend to do, before we can make useful suggestions. It would be appropriate to handle the age categories, at least initially, by using a separate dummy variable for each category except the first (which will be fitted by the intercept term in your model). You can then plot the coefficients against the midpoint of the category and consider whether to revise the model. You said that you have the age category, separately, for the husband and the wife. Thus, you would use two separate sets of dummy variables, one for the husband's age and the other for the wife's age. You may want to explore the possibility of interactions between the two ages. Please say more about the counts that you listed for 1985 and 1986 (I assume that those are two of the 20 years). They appear to be the frequency distribution of the numbers of divorces by one of the sets of age categories. If you are projecting divorce rates, and those counts represent the number of divorces in one year, what is the denominator for the rate? Do you have the denominator for each age category (and even the combination of husband's age category and wife's age category) or only for the year as a whole? Do the data come from a survey? If so, you will need to take the sampling design and the weights into account. What type of regression are you planning to use? Ordinary regression will probably not be appropriate for rates. You should consider Poisson regression (and perhaps negative binomial regression)? So far, I can envision a model that contains a time pattern (initially based on a dummy variable for each year after the first), effects for husband's age, and effects for wife's age (and perhaps some form of husband-wife interaction). Do you have covariates that you are planning to include? I look forward to seeing more information. David Hoaglin On Wed, Apr 25, 2012 at 12:36 AM, Shirley Sy <shirleysy@hotmail.co.uk> wrote: > Dear Statalisters, > I am a complete beginner at Stata so my question is very basic but I am having trouble finding an answer on the web. I am doing a time series regression project forecasting divorce rates. My data spans 20 years and for both husband and wife the 'age at divorce' variable is split into groups i.e it looks something like this: > > Year under 20 20 to 29 30 to 39 40 to 49 50 to 59 60plus not stated1985 458 1154 78 52 3 2 3 > 1986 221 956 50 59 9 5 0 > How would I run a regression with the total numbers in each age group? Would I use dummy variables? I understand how I would do it if I had individual ages but since this is a time series model and I have the total number in each age group, I am finding it slightly more complicated. > > ThanksShirley * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**FW: st: Regression with multiple age groups***From:*Shirley Sy <shirleysy@hotmail.co.uk>

**References**:**st: Regression with multiple age groups***From:*Shirley Sy <shirleysy@hotmail.co.uk>

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