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From |
gjhxmu@sina.com |

To |
statalist<statalist@hsphsun2.harvard.edu> |

Subject |
Re: AW: st: AW: AW: Something wrong with the -count- option in the -egen-? |

Date |
Thu, 13 Aug 2009 19:45:45 +0800 |

Martin, Thank you for your help, which let me undertand more. Best regards, Rose. ----- Original Message ----- From: Martin Weiss <martin.weiss1@gmx.de> To: <statalist@hsphsun2.harvard.edu> Subject: AW: st: AW: AW: Something wrong with the -count- option in the -egen-? Date: 2009-8-13 17:26:43 <> I would say that the "mistake" that you made is an obvious hazard, as the -sum- -total- and -count- functions for -egen- are not easily separated in users` heads, and the added complication of an -expression- being allowed as the argument compounds the problems. Admittedly, I had to read the definition in the -h egen, count()- to solve your puzzle. Still, you can combine the -count()- function with the -by- prefix, and it can be handy then to see how many non-missing entries there are for a certain variable... ************* clear* set obs 5 gen id=_n expand 10 set seed 43987 gen x=rnormal() //25 % artificially missing replace x=. if /* */ runiform()<0.25 //How many non-missing per group? bys id: egen mycount=/* */ count(x) list, noobs sepby(id) ************* HTH Martin -----Ursprüngliche Nachricht----- Von: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von gjhxmu@sina.com Gesendet: Donnerstag, 13. August 2009 11:16 An: statalist Betreff: Re: st: AW: AW: Something wrong with the -count- option in the -egen-? Martin， Thank you for your help, and now I know the inner rationale for -count- in the -egen-. The -total- option is helpful. BTW, what is the most value for -count- option in the -egen- ? I can get r(N) quickly after stand alone -count- . Best regards, Rose. ----- Original Message ----- From: Martin Weiss <martin.weiss1@gmx.de> To: <statalist@hsphsun2.harvard.edu> Subject: st: AW: AW: Something wrong with the -count- option in the -egen-? Date: 2009-8-13 17:02:02 <> BTW, the standalone -count- command leaves "r(N)" behind, so you can process the number further. If you want it in your dataset, you can use -egen, total()- ************* clear input x 1 2 3 5 . end egen yyy=/* */ total(x==2) list, noobs ************* HTH Martin -----Urspr黱gliche Nachricht----- Von: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von Martin Weiss Gesendet: Donnerstag, 13. August 2009 10:49 An: statalist@hsphsun2.harvard.edu Betreff: st: AW: Something wrong with the -count- option in the -egen-? <> Nothing is wrong, luckily... As -h egen- says about the -count- option: " creates a constant ... containing the number of nonmissing observations of exp." So the surprising result of your last line is easily explained: The -expression- fed to -count- evaluates to nonmissing -either 0 or 1- for every one of those five rows of your dataset, and -count- picks up this number. All it cares about is the fact that the expression is non-missing, not its content. If you want to -count-, use the standalone -count-... ************* clear input x 1 2 3 5 . end egen y=count(x) egen yy=count(x>2) egen yyy=count(x==2) //another xmpl, //20 is not even in the list of values egen yyyy=count(x==20) //the following dummy is counted //it has 5 non-missing entries... gen byte dummy=x==20 l,noobs //stand alone -count- cou if x==2 ************* HTH Martin -----Urspr黱gliche Nachricht----- Von: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von gjhxmu@sina.com Gesendet: Donnerstag, 13. August 2009 10:37 An: statalist Betreff: st: Something wrong with the -count- option in the -egen-? I typed the following in the stata and found -count- option didn't work well. Anything wrong? clear input x 1 2 3 5 . end egen y=count(x) egen yy=count(x>2) egen yyy=count(x==2) l,noobs +------------------+ | x y yy yyy | |------------------| | 1 4 5 5 | | 2 4 5 5 | | 3 4 5 5 | | 5 4 5 5 | | . 4 5 5 | +------------------+ Thank you for any help! Best regards, Rose * * 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/ * * 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/ * * 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/

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