random coefficient logit models / BLP estimation

[ebad(i)]

Hi all,
I am using blp command in Stata 12. This command is used for random coefficient discrete choice models when we use logit functions. Using this command gives me the error with sth that doesn't exist in variables. The error is as follow:
share variable must be within the interval 0,1
r(498);
Anyone knows what is the "share variable"? How can I solve the problem?

Many thanks,
Ebad

[Brett G.]

According to `help blp' :

Syntax

blp sharevar [varlist] [if] [in], endog(endogvars=inst) stochastic(svar1=dvars1,svar2=dvars2,..)
markets(marketvar) [draws(#) demofile(demodata) tolin(#) tolout(#) initsd(init_vals)
initdemo(init_vals) elast(price_var,mkt_num,prod_var) robust twostep noisily nocons]

The "share variable" is the dependent variable, which typically represents the market share of some product. Based on the error message, it looks like you're passing in a value of sharevar that is outside the valid range of [0,1]. All market shares are restricted to this interval.

HTH,

Brett

[Kuda Makoni]

I am running the same model but i am getting the following error message

unrecognized command: markets

What could i be doing wrong?

[Nick Cox]

blp sharevar [varlist] [if] [in], endog(endogvars=inst) stochastic(svar1=dvars1,svar2=dvars2,..)
markets(marketvar) [draws(#) demofile(demodata) tolin(#) tolout(#) initsd(init_vals)
initdemo(init_vals) elast(price_var,mkt_num,prod_var) robust twostep noisily nocons]

is one command line, not two or three. Don't start a new line with markets.

[Kuda Makoni]

Thank you, its now saying

file demodata.dta not found

How do i fix that?

[Nick Cox]

I don't know anything about this command except what I see in this thread. Evidently you need a Stata dataset demodata.dta for this example to work.

[Dimitriy V. Masterov]

If you type

net describe blp, from(http://fmwww.bc.edu/RePEc/bocode/b)
net get blp

you will get the auxilliary files like demodata.dta

[Kuda Makoni]

Thank you, now where do i get the instruments i am getting an error saying

instrument x12 not found

[Dimitriy V. Masterov]

In the helpfile for blp (which you can access with -help blp-), take a look at Example 2:

. use blp_demo,clear
...
. gen x12=x1^2

Presumably, that is where it comes from.

[Kuda Makoni]

How do i access the help file?

[Dimitriy V. Masterov]

See above:

In the helpfile for blp (which you can access with -help blp-), take a look at Example 2:

. use blp_demo,clear
...
. gen x12=x1^2

Presumably, that is where it comes from.