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# Re: st: how to do a weighted transition matrix

 From Hey Sky To statalist@hsphsun2.harvard.edu Subject Re: st: how to do a weighted transition matrix Date Fri, 29 Apr 2011 11:50:16 -0700 (PDT)

```Dear Nick

thanks for your time and kind answer.

I think now the question connects to how Stata deals weight.

what does it mean when I use aweight to the command tab? it seems it should not
change the result since the help file says aweight is inversely proportional to
the VARIANCE of an observation, usually represent averages, but not the value
itself. but it does have difference when with/out using the weight.

do you think the weight for xttrans in Stata, if it has the option, has the same
principle as tab?  that is, the weight multiplies the value? if not, what would
it be to get the weighted value with command tab?

thanks for your time and kind answer again

Nan
from Montreal

----- Original Message ----
From: Nick Cox <njcoxstata@gmail.com>
To: statalist@hsphsun2.harvard.edu
Sent: Fri, April 29, 2011 1:54:45 PM
Subject: Re: st: how to do a weighted transition matrix

Thanks for the detail. From what you tell us, I gather that the
weighted matrix of transition frequencies  is just the actual matrix
multiplied by the constant. The transition probabilities are
unaffected by a multiplicative constant.

Nick

On Fri, Apr 29, 2011 at 5:37 PM, Hey Sky <heyskywalker@yahoo.com> wrote:
> Dear Nick
>
>
> my research topic is about the transition probability from one state to
>another,
> e.g., white/blue collar job and self-employment within an unbalanced panel.
all
> the three states are mutural exclusive dummy variables. the weight is a
>constant
> number but not integer. it adjust the percentage of different people groups,
> e.g., there is too many refugee in the survey but less other immigrants so
that
> the stats bureau uses the weight to adjust it back to represent the  real
>world.
>
>
> the following created data are almost the same with the actural one, though I
>am
> not sure about the value of the weight. I checked it once long time ago and
> vaguely remember it is just a constant number (I cannot check not due to the
> data is not at hand). I used xttrans to get the transition matrix but I have
> been required to use weights otherwise I cannot take the results to the
public.
>
>
> hope I make my question clear and thanks for any suggetsions.
>
> clear
> input id time w b s weight
> 1 1 1 0 0 1.8
> 1 2 1 0 0 1.8
> 1 3 0 1 0 1.8
> 2 1 0 1 0 1.8
> 2 2 0 1 0 1.8
> 2 3 0 0 1 1.8
> 3 1 0 0 1 1.8
> 3 2 0 1 0 1.8
> 3 3 . . .  1.8
> 4 1 0 0 1 1.8
> 4 2 0 1 0 1.8
> 4 3 1 0 0 1.8
> end
>
>
> Nan
> from Montreal
>
>
>
>
> ----- Original Message ----
> From: Nick Cox <njcoxstata@gmail.com>
> To: statalist@hsphsun2.harvard.edu
> Sent: Fri, April 29, 2011 12:06:46 PM
> Subject: Re: st: how to do a weighted transition matrix
>
> More explanation would help. Where do the weights come from? Do they
> weight the transitions? The earlier state? The later state? Are they
> integers or not? What is your data structure? Which variables hold
> which information? Do you expect a precise answer to a vague question?
>
> At its easiest, this sounds like a transition matrix multiplied
> elementwise by a weights matrix, so save the matrices independently
> and do the multiplication in Mata.
>
> Nick
>
> On Fri, Apr 29, 2011 at 4:57 PM, > Nan from Montreal, a.k.a. Hey Sky
> <heyskywalker@yahoo.com> wrote:
>
>> I have to do a weighted transition matrix but it is not an option for the
>> command xttrans.
>>
>> I have searched the archives but did not find any discussion about
>> this question.
>> did anyone experience this before and any (other) method to deal with it?
>
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```