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From |
Nick Cox <[email protected]> |

To |
"'[email protected]'" <[email protected]> |

Subject |
RE: st: "table" showing summary of ~100 ternary variables? |

Date |
Sun, 31 Oct 2010 19:11:16 +0000 |

As Phil surmises, there are various user-written commands (but not functions; outside of Mata, users may not write functions; in any case what Michael is asking for can only be done within Stata by a command) which are alternatives for at least some of this problem. See SJ-5-1 st0082 . . . . . . . . . . . . . . . Tabulation of multiple responses (help _mrsvmat, mrgraph, mrtab if installed) . . . . . . . . B. Jann Q1/05 SJ 5(1):92--122 introduces new commands for the computation of one- and two-way tables of multiple responses and -tabm- from the -tab_chi- package on SSC. -tabm- was the subject of a thread earlier this month (October), so see the Statalist archives for some discussion. Given Phil's fake dataset tabm y* shows the frequencies of y1-y5 on the categories defined and -tabulate- options for a two-way table may be added. Ben's alternatives are documented in detail in his paper, so I'll not repeat that here. Nick [email protected] Phil Schumm I expect that there is probably a user-written program to do this, but it's not too difficult to do from first principles. We'll start by generating a dataset similar to what you've described: set obs 100 gen id = _n lab def mylab 1 "Correct" 2 "Incorrect" 3 "No response" 4 "Missing" set seed 123456789 forv i = 1/5 { gen byte y`i' = cond(runiform()<0.95, ceil(runiform()*3), 4) lab val y`i' mylab } replace y5 = 2 if y5==1 This generates 5 variables y1-y5, each taking values 1, 2, 3 or 4. You'll notice I've used 4 for the "missing" values here, only because that'll give you more flexibility for where the corresponding column appears in the final table (i.e., if we left missing values as ".", we wouldn't be able to place a summary column after that one). As you can see, each variable takes values 1-3 with probability 1/3 each, and is missing in 5% of cases. Note that I've also modified y5 so that it doesn't contain any correct responses, because you want to make sure your code can handle such cases. Now, the first trick is to reshape your data into long form: reshape long y, i(id) j(Var) Note that we could have used -stack- here instead, and in fact, that would have been more convenient if our variables weren't named systematically as they are here. Since we want to add a column for the proportion of correct responses, we'll add a corresponding observation for each variable whose values we'll fill in later (if you wanted to add multiple summary columns, you could add additional observations here): set obs `=c(N) + 1' replace y = 5 if _n == _N lab def mylab 5 "Prop. correct", add Next, we'll generate our cell counts by using -collapse-, but first we'll use -fillin- to make sure that all of our cells are represented (even if their observed counts are zero): fillin Var y collapse (count) cnt=id, by(Var y) Note that we are also using -fillin- here to propagate the observation we added above to hold the proportion of correct responses across all of the variables. Now, we'll compute the proportion correct (as a proportion of values 1-3) for each variable: egen correct = max((y==1)*cnt), by(Var) egen nonmiss = sum(inlist(y,1,2,3)*cnt), by(Var) replace cnt = correct / nonmiss if y == 5 And finally, we can use -tabdisp- to create our table: . tabdisp Var y if !mi(Var), c(cnt) format(%9.2g) -------------------------------------------------------------------- | y Var | Correct Incorrect No response Missing Prop. correct ----- +-------------------------------------------------------------- 1 | 34 37 25 4 . 35 2 | 26 35 33 6 . 28 3 | 25 32 40 3 . 26 4 | 32 27 35 6 . 34 5 | 0 62 34 4 0 -------------------------------------------------------------------- where I've used my text editor to narrow some of the columns so that the table doesn't get wrapped by people's mailers. Of course, there are several ways we might embellish this -- this merely illustrates one possible strategy for achieving the desired result. Michael Costello > I have about 100 ternary variables (0=incorrect, 1=correct, 2=No > Response, .=Missing) and I would like to get a table of the > responses that looks like this: > > ------------------------------------------------------- > | | Correct Incorrect No Response . > ----------+-------------------------------------------- > Var1 | 2 21 4 21 > Var2 | 8 19 13 18 > Var3 | 30 19 4 19 > Var4 | 18 21 47 22 > Var5 | 11 27 8 30 > > Maybe I'd even like to add in a proportion of correct or ratio of > correct to incorrect into the table. > > Is there a function to do this or something reasonable similar? * * 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: "table" showing summary of ~100 ternary variables?***From:*Michael Costello <[email protected]>

**Re: st: "table" showing summary of ~100 ternary variables?***From:*Phil Schumm <[email protected]>

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