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From |
Nick Darson <nick.darson@googlemail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: creating cross tables/ matrices with expected/ observed frequencies from long data set |

Date |
Mon, 24 Sep 2012 08:36:25 +1000 |

Nick, thanks for your reply. The first question simply asked for a normal cross-table (with frequencies of events A & B). I was able to get this through keep and reshape (and saving matrices and matrices to dta- sets). Just took a while. The second table I am looking for is not a normal cross-table - I need the product of a variable of two groups (classical matrix multiplication) and I also cannot simply collapse the data set to one observation per individual (as there are probabilities for each option from each individual). I can do this too by droping all variables, saving each data set, converting it to a matrix in another set, then multiplying it and saving it again...and so orth Again just not very handy..... therefore I posted my questions and was wondering whether anyone knows a command/ user written program that would facilitate this analysis.. it seems like not... lesson learnt (or maybe I used the wrong header/ described my problem not sufficient enough). In any case, I wanted to take the opportunity thank you and everyone who contributes to this mailing list for their generous voluntary support!!! This was one of the reasons why I decided to purchase a permanent license for Stata 12!! so, thanks guys :-) Nick Darson On Sat, Sep 22, 2012 at 7:58 PM, Nick Cox <njcoxstata@gmail.com> wrote: > Sorry, but I am not clear how the second question differs from the first. > > One table you are asking for has 300 columns (one for each ID). > Really? When I have that many columns, I give up on conventional > tables and just go for -list-s. -groups- (SSC) shows my strategy in > action, although I am not promising that it is an answer to any > problem of yours. > > On Sat, Sep 22, 2012 at 9:48 AM, Nick Darson <nick.darson@googlemail.com> wrote: >> Well, if there is not other solution, I guess I will have to reshape >> the data. I just wanted to double check whether there is a "tab"-like >> command that can create cross-tabs of different groups from the same >> variable.... >> >> What about the second question (for the expected frequencies)? Is >> there any table function (in the sense of "list") that simply shows >> the values of a group from a variable instead of describing its >> summary/ modes/ etc? >> >> BTW: Thanks for the reply, Nick! >> >> >> >> On Sat, Sep 22, 2012 at 5:16 PM, Nick Cox <njcoxstata@gmail.com> wrote: >>> I think that this question is self-cancelling, as I guess that you >>> need to restructure your data to get tables that you want, but seem to >>> rule that out as an acceptable solution. >>> >>> Nick >>> >>> On Sat, Sep 22, 2012 at 1:35 AM, Nick Darson <nick.darson@googlemail.com> wrote: >>> >>>> I would like to create several tables/matrices with expected >>>> frequencies and observations (to be able to carry out a Chi Square >>>> test of how well my model describes the data). >>>> I have the following data set (each person chose from 2 sets, the >>>> first one containing 3 option, the second one containing 4 options), >>>> with ID=individuals (300), set=choice set, option= option, choice= >>>> chosen option (dummy), Prob= expected probability for each individual >>>> based on my random-effects logit model. >>>> >>>> ID Set Option Choice Prob >>>> 1 1 A 0 0.2 >>>> 1 1 B 1 0.7 >>>> 1 1 C 0 0.1 >>>> 1 2 D 0 0.1 >>>> 1 2 E 0 0.2 >>>> 1 2 F 1 0.4 >>>> 1 2 G 0 0.3 >>>> 2…. >>>> >>>> First I would need a cross-table with observed frequencies for the two >>>> choice sets (looking as follows): >>>> A B C >>>> D >>>> E >>>> F >>>> G >>>> >>>> I am familiar with the tab-command, but a bit lost how do to obtain >>>> the table given my data-set arrangement? Any help would be >>>> appreciated. >>>> >>>> >>>> Then I would need the same table as above, but with expected (joint) >>>> probabilities instead of observed frequency. For this, I had the >>>> following strategy in mind: >>>> 1.) Create 2 matrices, one for each choice set >>>> 2.) Transpose one matrix and multiply to obtain joint probability >>>> >>>> For 1.), I would need one table with the probabilities listed (column= >>>> Individuals; rows= options) as follows: >>>> >>>> ID1 ID2 ID3 ….. >>>> A 0.2 ….. >>>> B 0.7 >>>> C 0.1 >>>> (and same table/ matrix for set 2). >>>> How would I do this in Stata? To my understanding, Tabs and tabstats >>>> only provide summaries etc, but I want the original value of prob >>>> listed? >>>> Any help would be appreciated! >>>> BTW: this is a simplification of the original data set (more sets and >>>> options) and I would like to do several things in one set…therefore, I >>>> “keep”/”reshape” combos would not be suitable. > > * > * 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/

**References**:**st: creating cross tables/ matrices with expected/ observed frequencies from long data set***From:*Nick Darson <nick.darson@googlemail.com>

**Re: st: creating cross tables/ matrices with expected/ observed frequencies from long data set***From:*Nick Cox <njcoxstata@gmail.com>

**Re: st: creating cross tables/ matrices with expected/ observed frequencies from long data set***From:*Nick Darson <nick.darson@googlemail.com>

**Re: st: creating cross tables/ matrices with expected/ observed frequencies from long data set***From:*Nick Cox <njcoxstata@gmail.com>

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