```Date: Sat, 14 Jan 2006 12:51:09 -0500 Reply-To: "Meyer, Gregory J" Sender: "SPSSX(r) Discussion" Comments: To: lucameyer@tiscali.it From: "Meyer, Gregory J" Subject: Re: Percentiles Content-Type: text/plain; charset=us-ascii Luca, assuming you are interested in using a sample determined percentile, here's one way to do what you want. * Convert observed scores to standardized Z scores using the M and SD from your sample . DESCRIPTIVES VARIABLES= X (X_zscore) /SAVE . * Because a Z score of -.84 cuts off the lowest 20% of the distribution, recode based on the X_zscore variable. RECODE r_zscore (Lowest thru -.84 = 1) (ELSE = 0) INTO Y . EXECUTE . * Note, the cut off value can be modified to any percentile you desire using the normal curve equivalents found in the back of any stats book Greg | -----Original Message----- | From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] | On Behalf Of Luca Meyer | Sent: Saturday, January 14, 2006 2:59 AM | To: SPSSX-L@LISTSERV.UGA.EDU | Subject: Percentiles | | Is there any easy way to compute a X percentile of a | variable? What i need is something like: | | IF X<=PERCENTILE(20) Y=1. | | That is: if the value of X for each single case is lower or | equal to the 20% percentile of X then Y=1. | | Is this somehow possible? | | Thanks, | Luca | | Mr. Luca MEYER | Survey research, data analysis & more: http://www.lucameyer.com/ | Tel: +390122854456 - Fax: +391782232575 - Mobile: + 393394950021 | ```

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