Solomon Method

Exploratory and confirmatory factor analyses are two important consecutive steps in an overall analysis process. To carry out the analyses, researchers usually collect a single sample, and then split it into two halves. As no specific splitting methods have been proposed to date in the context of factor analysis, researchers use a random split approach. However, random splitting can provide samples that are clearly not equivalent. Of course, random splitting could be used a number of times until equivalent subsamples are obtained. It must be said that this approach is not optimal from the point of view of computing time.

We propose Solomon as a method to split samples into equivalent subsamples similar to one method that has already been proposed in the context of multivariate regression analysis.

We implemented Solomon method in three different statistical programs:

• The R script "solomon.r". It is a script that uses only native functions in R, so no packages needs to be downloaded to use it. In order to use it, the researcher has to store participants' responses in a text file, update the name of the input and output files, and to execute the script. In the output file, the first column indicates the assignment of each row to one or the other subsample.

Download solomon_r.zip

The SPSS script "solomon.sps". Again, in order to use it the researcher must have participants' responses in a SPSS data file, and to execute the script. A new data file is generate with the first variable indicating the assignment of each row.

Download solomon_spss.zip

Finally, we implemented Solomon method in our program to compute factor analysis, that can be downloaded free from the site (/media/upload/domain_2082/arxius/Utilitats/factor/index.html). To help the researcher to use Solomon method insight FACTOR, a video tutorial is also available at the web site.