Re: st: graph results of bitest stratified with by(var)

[Nick Cox <njcoxstata@gmail.com>]

-search foreach- does exactly what you ask, namely point to sources on
-foreach-.

But -help statsby- does even better.

Here's a dopey example.

sysuse auto, clear
statsby N=r(N) k=r(k) p_l=r(p_l) p_u=r(p_u) , by(rep78): bitest
foreign=.2
list

Nick
njcoxstata@gmail.com

On 23 January 2014 17:55, Michael McCulloch <mm@pinestreetfoundation.org>

> Thank you Richard, that's exactly what I'm wanting to achieve.
> I understand now that -bysort- clears the scalars at each re-call.
>
> Can you point me to primers so I can learn how to wrap this into a -foreach- / -levelsof- loop?


On Jan 23, 2014, at 5:45 AM, Richard Goldstein wrote:
>
>> If I understand what you want correctly, you cannot do it with bysort
>> because each time you do the test the set of returned values (the
>> "r()"'s) will be replaced and the old ones lost
>>
>> you can do this within a -foreach- loop (you may need -levelsof- first)
>> in which you quietly do the -bitest- and then list your results for that
>> test and then do the next -bitest-, etc.
>>
>> here is an example of how to use the returned values:
>>
>> . sysuse auto
>>
>> . bitest foreign=.2
>>
>>    Variable |        N   Observed k   Expected k   Assumed p   Observed p
>> -------------+------------------------------------------------------------
>>     foreign |       74         22         14.8       0.20000      0.29730
>>
>>  Pr(k >= 22)           = 0.029904  (one-sided test)
>>  Pr(k <= 22)           = 0.984075  (one-sided test)
>>  Pr(k <= 7 or k >= 22) = 0.041800  (two-sided test)
>> r; t=0.09 8:39:38
>>
>> . di r(N) _skip(2) r(P_p) _skip(2) r(k)/r(N) _skip(2) r(p)
>> 74  .2  .2972973  .04179963
>>
>> I have not put headers on the columns and have not done several other
>> things you might want (e.g., print format for results) but this should
>> give the basic idea, assuming I have correctly understood you

On 1/23/14, 12:57 AM, Michael McCulloch wrote:

>>> I am using bitest for a two-sided test on whether the mean of varB is different than 0.2, and testing on each level of varA:
>>>      bysort varA:    bitest varB=.2
>>>
>>> varA has ~30 values. I wish to display these in a table (showing N, observed p,
>> expected p, and the two-sided p-value), without manual cut-and-paste, as
>> the test
>> will be used to monitor an ongoing training program.
>>>
>>> I note that the results of bitest are stored as:
>>>      r(N)           number N of trials
>>>      r(P_p)         assumed probability p of success
>>>      r(k)           observed number k of successes
>>>      r(p_l)         lower one-sided p-value
>>>      r(p_u)         upper one-sided p-value
>>>      r(p)           two-sided p-value
>>>
>>> However, I do not know how one uses these r(**) values. Can anyone suggest how one
>> would go about this?
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