=========================================================================
Date:         Wed, 12 Jul 2006 09:57:43 -0400
Reply-To:     Statisticsdoc <statisticsdoc@cox.net>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Statisticsdoc <statisticsdoc@cox.net>
Subject:      Re: percentile scores
Comments: To: Humphrey <humphreyyy1000@yahoo.com>
In-Reply-To:  <20060712091219.2812.qmail@web30002.mail.mud.yahoo.com>
Content-Type: text/plain; charset="iso-8859-1"

Humphrey,

There are two ways to compute percentile scores in SPSS:

You can use menus to compute percentile ranks as follows:

1.)    Under the Transform menu, choose Rank Cases…
2.)    Choose the variable containing the raw test scores
3.)    Click on the Ties… box and choose High as the Rank Assigned to Ties
4.)    Click on the Rank Cases: Types… box and Check Fractional rank as %
5.)    Uncheck Rank (Unless you want cumulative frequencies)
6.)    Click on OK
7.)    SPSS will label the variable that contains the percentile ranks
"PCT001".
You can rename PCT001 with a clearer name if you wish.

You can also standardize the variable, and then use COMPUTE to transform the
z-score into the corresponding percentile score, but I would not recommend
that unless you are reasonably sure that your data are normally distributed.
This method is handy when you are dealing with a very large file of test
scores, as you are, that are normally distributed.  You can use the menus to
compute percentile scores via standard scores as follows:

1.)    Under the Analyze menu, choose Descriptive Statistics…, Descriptives
2.)    Choose the variable containing the raw test scores
3.)    Check the box Save Standardized values as variable.
4.)    Click on OK.
5.)    SPSS will label the variable that contains the standard scores "zx".
6.)    Under the Transform menu, choose Compute…
7.)    Fill in zx as the Target Variable and Percentile Rank as the label.
8.)    In the box Numeric Expression type in:  CDFNORM(zx)*100
9.)    Click on OK

Again, you can rename the variable with the percentile scores with a clearer
name.

You may wish to set your output file to record syntax that you can cut,
paste and re-use.

HTH,

Stephen Brand

For personalized and professional consultation in statistics and research
design, visit
www.statisticsdoc.com


-----Original Message-----
From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU]On Behalf Of
Humphrey
Sent: Wednesday, July 12, 2006 5:12 AM
To: SPSSX-L@LISTSERV.UGA.EDU
Subject: percentile scores


Dear everyone,
  How can I get percentile scores for each case who has taken a reading test
in a population of 10000?
  I have got their total raw scores but I want percentiles which show thier
performance relative to the performance of others?
  Best
  Humphrey



---------------------------------
Do you Yahoo!?