# Re: AW: st: imputing continuous values when respondents select categories, e.g., income category

 From Richard Williams To "statalist@hsphsun2.harvard.edu" , "statalist@hsphsun2.harvard.edu" Subject Re: AW: st: imputing continuous values when respondents select categories, e.g., income category Date Fri, 24 Apr 2009 17:09:40 -0500

```At 03:29 PM 4/24/2009, Alan Acock wrote:
```
Thanks for recommending intreg. I was not familiar with this command. When I run the example in the reference manual, the estimated income is not always within the limits of the interval the respondent selected. Using their example and predicting est_income, here are the first 10 observations:
```  +---------------------------+
| wage1   wage2    est_wage |
|---------------------------|
1. |     .       5    4.266946 |
2. |     5      10    7.502522 |
3. |     5      10    10.19239 |
4. |    10      15    8.924339 |
5. |     .       5    8.116896 |
|---------------------------|
6. |     .       5     10.2202 |
7. |     .       5    10.35355 |
8. |     5      10   -2.894233 |
9. |     5      10    13.32243 |
10. |     5      10    9.792462 |

```
Some estimated values are well outside of the interval. Is it recommended to simply replace these with the interval boundaries?
```
```
There is nothing that says the estimated wages have to lie within the interval. The est_wage is just E(Y | X). Just as in regular regression, the estimates will sometimes be higher than the observed value, sometimes lower. My guess is that replacing them with the interval boundaries would be a terrible idea.
```
```
The intreg approach might be good if income was your dependent variable, but by the way you are talking I'm guessing you really want it as an independent variable.
```
```
Sometimes people just use the midpoint of the interval; other times they will just break income up into dummy variables. I believe there are other more advanced methods but I am not that familiar with them.
```

-------------------------------------------
Richard Williams, Notre Dame Dept of Sociology
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