*! version 1.0 22jan2015

help sumscale

Title

sumscale - generating summated scales

sumscale
[, f1(varlist) f2(varlist) etc.... options]

Description

sumscale generates new variables by combining the scores of a set of
ordinal/dummy variables of an underlying factor/construct.

There are two ways in which sumscale combines the scores of a set of
ordinal variables/items: 1) take the average and 2) take the sum. The
first option is the default of sumscale. The second option can be
chosen by adding fsum as shown below. sumscale displays also
some descriptive statistics as well as the Cronbach Alpha coefficient
of reliability for the newly generated summated scale/s.

sumscale allows also for combining the scores of a set of dummy variables.
This is simply done by taking the sum of the scores. This option can be
chosen by adding fdummy as shown below. For the resulting variables
the program displays the descriptive statistics and the Kuder-Richardson
coefficient of reliability.

options

fsum sums/aggregates the scores of a set of ordinal variables/items
fdummy sums/aggregates the scores of a set of dummy variables/items

KW: summated
KW: scale
KW: reliability
KW: alpha
KW: factor analysis

Examples

. use http://www.ats.ucla.edu/stat/stata/output/m255, clear

. keep item13 item14 item15 item16 item32 item41

. sumscale, f1(item13 item14 item15 item16) f2(item32 item41)

. sumscale, f1(item13 item14 item15 item16) f2(item32 item41) fsum

. use http://www.ats.ucla.edu/stat/stata/output/m255, clear

. keep item13 item14 item15 item16 item32 item41

. qui recode item13 item14 item15 item16 item32 item41 (1 2 3 = 0) (4 5 = 1)

. sumscale, f1(item13 item14 item15 item16) f2(item32 item41) fdummy

Author

Mehmet Mehmetoglu
Department of Psychology
Norwegian University of Science and Technology
mehmetm@svt.ntnu.no