My previous sentences should have been:
"50=total high skilled workers."
"Put in other words, 0.4 can be read as the probability of sampling a black
high skilled worker from a sample of high skilled workers (i.e.:
20/50=0.4)."
I apologize for these mistakes,
Carlo
-----Messaggio originale-----
Da: Carlo Lazzaro [mailto:carlo.lazzaro@tin.it]
Inviato: martedì 19 luglio 2011 12.19
A: 'statalist@hsphsun2.harvard.edu'
Cc: 'nicostat@gmail.com'
Oggetto: R: conditional probability
Nico wrote:
"and prob(B|H) is the jointly probability to hiring a black worker
conditional on being a H worker"
High skilled Low skilled Total
----------------------------------------------
Black 20 40 60
Others 30 50 80
----------------------------------------------
Total 50 90 140
P(B|H)=probability of hiring a black worker conditional on being high
skilled [by the way, this is a conditional probability, not a joint one].
P(B|H)=P(B,H)/P(H)
Using data from the table above:
P(B|H)=[(20/140)/(50/140)]=0.4
Where:
20= high skilled black workers;
140= total observations;
50=total skilled workers.
Put in other words, 0.4 can be read as the probability of sampling a black
skilled worker from a sample of skilled workers (i.e.: 20/50=0.4).
Beware of not reversing the condition: P(B|H) is conceptually different from
P(H|B), even though the resulting probabilities may look not so different.
In Stata, you can type something like this:
gen P(B|H)=[(20/140)/(50/140)].
Obviously, you may want to replace the number between brackets with var
names.
HTH and Kind Regards,
Carlo
-----Messaggio originale-----
Da: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] Per conto di
nicostat@gmail.com
Inviato: martedì 19 luglio 2011 0.41
A: statalist@hsphsun2.harvard.edu
Oggetto: st: conditional probability
Dear Statalist,
I don't know in stata how can estimate this kind of probabilities
probHB=prob(B|H)prob(H)/prob(B|H) prob(H) + prob(W|L) prob(L)
where probHB is the probability to hire a High skill worker in the
market for black worker
and prob(B|H) is the jointly probability to hiring a black worker
conditional on being a H worker.
thanks in advance for your help
Nico
*
* 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/
*
* 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/
