Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

From |
ajjee <ajjee1@yahoo.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
st: Re: Making Cohorts |

Date |
Thu, 28 Oct 2010 04:14:52 -0700 (PDT) |

Dear I want to implement the following strategy on my data. Consider now the basic linear individual effect model yit = ai + bXit + uit i = 1,…N; t = 1,…T eq(1) where Xit is a (K x 1) vector of explanatory variables which we assume exogenous to the model, index t and i refer to time and individuals respectively. Assuming, for simplicity, that there is a unique regressor (K = 1), if we aggregate all observations to cohort level, the resulting model can be written as (y-bar)_ct = (a-bar)_ct + b(x-bar)_ct + (u-bar)_ct c = 1,…C where (x-bar)_ct is the average value of all observed xit’s in cohort c at time t, and analogously for the other variables in the model. The resulting data set is a pseudo panel with repeated observations over T periods and C cohorts. now I want to make cohorts (say for) birth year and then want to aggregate the data as above. But I have 15 countries also and I want to analyse particular attitudes in countries based on three year surveys(6 waves). Thanks and Regards, Ajjee Maarten buis wrote: > > --- On Thu, 28/10/10, ajjee <ajjee1@yahoo.com> wrote: >> But I am still confused about COHORT. When I create this by >> cohort=year-age, now it gives me year of birth of each >> respondent. Now I want to group each respondent in a unique >> cohort. I'm quoting procedure from a paper >> >> "Define C cohorts, which are groups of individuals sharing >> some common characteristic like sex or date of birth. These >> groups are defined in such a manner that each individual is >> a member of exactly one cohort, and remains a member of this >> cohort for all periods. For example, a particular cohort may >> consist of all male individuals born in 1945–1949." > > So, year of birth is one form of cohort: it defines groups that > are born in a given year. The fact that this confuses you is > an example of common mistake: Just because something has its > own name does not mean that it is special or difficult. A > cohort, as you defined it, is just another name for a variable > that you want to treat as categorical. > > If you want another categorization, then you need to tell us > exactly what you want. As the definition you quoted above says > there are an extremely large number of ways in which you can > group observations. > > Hope this helps, > Maarten > > -------------------------- > Maarten L. Buis > Institut fuer Soziologie > Universitaet Tuebingen > Wilhelmstrasse 36 > 72074 Tuebingen > Germany > > http://www.maartenbuis.nl > -------------------------- > > > > > * > * 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/ > > -- View this message in context: http://statalist.1588530.n2.nabble.com/Making-Cohorts-tp5681938p5682193.html Sent from the Statalist mailing list archive at Nabble.com. * * 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**:**Re: st: Re: Making Cohorts***From:*Maarten buis <maartenbuis@yahoo.co.uk>

**References**:**st: Making Cohorts***From:*ajjee <ajjee1@yahoo.com>

**Re: st: Making Cohorts***From:*Maarten buis <maartenbuis@yahoo.co.uk>

**st: Re: Making Cohorts***From:*ajjee <ajjee1@yahoo.com>

**Re: st: Re: Making Cohorts***From:*Maarten buis <maartenbuis@yahoo.co.uk>

- Prev by Date:
**st: Rolling Window with Panel Data** - Next by Date:
**RE: st: RE: creating an index variable: number of presentations to hospital by participant** - Previous by thread:
**Re: st: Re: Making Cohorts** - Next by thread:
**Re: st: Re: Making Cohorts** - Index(es):