ppm use for imputation

[abdelilah arredouani]

Hi all,
i have 57 variables and many of them have missing values. i have tried mi with chained equations but it introduces negative values. i am trying to use ppm and i am using the code below but i get errors:
mi impute: invalid method ppm
Method ppm is not one of the officially supported mi impute methods. If you are adding a new user-defined method to mi impute, you need to create a parser named
mi_impute_cmd_ppm_parse.ado and an imputer named mi_impute_cmd_ppm.ado; see mi impute user


any suggestion what am i adoing wrong

mi set mlong
mi register imputed cnv bmi waistcm hipcm whratio glucosemmoll hba1c insulinmcunitml cpeptidengml homarir homab hdl ldl tcholesterol triglyceridemmoll systolicbp diastolicbp pulse  bodyweighkg heightinm albumingl alkalinephosphataseul altgptul astgotul calcium calciumcorrected chloridemmoll bicarbonatemmoll bilirubintotalumoll creatinekinaseul creatinineumoll vitD estradiopmlll ferritinmcgl folatenmoll freethyroxinepmlol freetriiodothyroninepmll glutamyltransferaseul homocysteineumoll ironumolml magnesiummmoll  phosphorusmmoll potassiummmoll shbgmnmoll sodiummmoll testosteronetotalnmoll tshmiul tibc totalproteingl ureammoll uricacidumoll vitaminb12pmoll ffmkg fat fatmasskg  fatmassindexkgm2 vatmasskgs bai  

mi impute ppm cnv bmi waistcm hipcm whratio glucosemmoll hba1c insulinmcunitml cpeptidengml homarir homab hdl ldl tcholesterol triglyceridemmoll systolicbp diastolicbp pulse  bodyweighkg heightinm albumingl alkalinephosphataseul altgptul astgotul calcium calciumcorrected chloridemmoll bicarbonatemmoll bilirubintotalumoll creatinekinaseul creatinineumoll vitD estradiopmlll ferritinmcgl folatenmoll freethyroxinepmlol freetriiodothyroninepmll glutamyltransferaseul homocysteineumoll ironumolml magnesiummmoll phosphorusmmoll potassiummmoll shbgmnmoll sodiummmoll testosteronetotalnmoll tshmiul tibc totalproteingl ureammoll uricacidumoll vitaminb12pmoll ffmkg fat fatmasskg fatmassindexkgm2 vatmasskgs bai= age, add(10)

note: missing-value pattern is monotone; no iteration performed

stat 15.1 mac

thanks in advance

[Maarten Buis]

I suspect you want to use predictive mean matching. In that case, the abbreviation is pmm rather than ppm

[Marcos Almeida]

You may wish to read this thread, particularly #2.

[abdelilah arredouani]

excellent thanks.