[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]
Re: st: MI questions
> Thanks, Marteen.
-- Christopher Parker <email@example.com> wrote:
>> x1-x3 are not observed in dataset1, but I need them for theoretical
>> purposes. Therefore, I treat them as missing data in dataset1 and
>> impute them from dataset2 using demographic information common to
>> Here's the problem: x1-x3, the imputed data, have negative values
>> after merging with dataset1. There shouldn't be negative values.
>> These are dichotomous 0-1 values when observed in dataset2.
> This seems to be a problem with Amelia II and not with Stata. I quick
> look at the documentation of Amelia II suggests that it primarily uses
> a multivariate normal to do the imputations. That is, your imputed
> values are drawn from a normal distribution thus explaining the
> negative values. However, all is not lost since the documentation also
> states that: "Amelia includes some limited capacity to deal directly
> with ordinal and nominal variables and to variables that require other
> transformations". And if that doesn't work you can always use -ice-,
> which is designed to deal with combinations of normal, dichotomous,
> ordinal, count, whatever data. Actually, I would do both and see if
> they both result in similar results, just to make sure that your
> outcomes aren't the result of some artifact of the algorithm.
> Hope this helps,
> Maarten L. Buis
> Department of Social Research Methodology
> Vrije Universiteit Amsterdam
> Boelelaan 1081
> 1081 HV Amsterdam
> The Netherlands
> visiting address:
> Buitenveldertselaan 3 (Metropolitan), room Z434
> +31 20 5986715
> Yahoo! Messenger - with free PC-PC calling and photo sharing.
> * For searches and help try:
> * http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
* For searches and help try: