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Re: st: cascading dummies
From
Shikha Sinha <[email protected]>
To
[email protected]
Subject
Re: st: cascading dummies
Date
Mon, 1 Oct 2012 13:07:00 -0700
Thanks!
Shikha
On Mon, Oct 1, 2012 at 12:15 PM, Nick Cox <[email protected]> wrote:
> As Richard said, Stata can tell you:
>
> . findit cascade
>
> STB-6 srd11 . . . . . . . . . Generating ordered "cascading" dummy variables
> (help cascade if installed) . . . . . . . . . . . . . . . R. Goldstein
> 3/92 pp.19--22; STB Reprints Vol 1, pp.190--194
> add a set of new dummy variables that are cascading; that is,
> 0/1 variables are created where a 1 is given if the case has
> the value <= value of lowest category
>
> Accessible at http://www.stata.com/products/stb/journals/stb6.pdf
>
> Nick
>
> On Mon, Oct 1, 2012 at 7:59 PM, Shikha Sinha <[email protected]> wrote:
>> Thanks Richard!
>>
>> very helpful. What is the full reference of STB article, I am unable to find it.
>
> On Mon, Oct 1, 2012 at 11:39 AM, Richard Goldstein
>> <[email protected]> wrote:
>
>>> neither is wrong or right -- they answer slightly different questions; A
>>> asks for each dummy whether, and by how, much it is different from the
>>> reference group (you do realize that you should only include 4 of the
>>> dummies, right?); B asks whether each differs from the preceding level
>>>
>>> you can -findit cascade- to find a program I wrote to implement
>>> cascading dummies; the help file, and even more the STB article,
>>> discusses the differences; note that you can obtain the answer to either
>>> question by following up the original method of forming the variables
>>> with the appropriate -test- command(s)
>
> On 10/1/12 2:31 PM, Shikha Sinha wrote:
>
>>>> Recently, I came across a new way of creating dummies and I wonder
>>>> what the group thinks about this form.
>>>>
>>>> The independent variable X is coded as 1- very poor, and 5 as very
>>>> rich. I want to estimate the effect by wealth quintile. I created the
>>>> dummy the following ways, but I was told that this is wrong (A is
>>>> wrong). The correct way to construct dummy is B and is called
>>>> cascading dummies. I have never come across this before and would
>>>> appreciate if you could shed light on the difference between the two
>>>> and which is the correct way of creating dummies.
>>>>
>>>> A:
>>>> id Y X1 (scale of 1-5), dum1 dum2 dum3 dum4 dum5
>>>> 1 100 5 0 0 0 0 1
>>>> 2 200 4 0 0 0 1 0
>>>> 3 300 3 0 0 1 0 0
>>>> 4 239 2 0 1 0 0 0
>>>> 5 345 1 1 0 0 0 0
>>>>
>>>>
>>>> B:
>>>> id Y X1 (scale of 1-5), dum1 dum2 dum3 dum4 dum5
>>>> 1 100 5 1 1 1 1 1
>>>> 2 200 4 1 1 1 1 0
>>>> 3 300 3 1 1 1 0 0
>>>> 4 239 2 1 1 0 0 0
>>>> 5 345 1 1 0 0 0 0
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