Presenting the scale

Here is the checklist of points to cover when presenting your scale:

• • A statement of what the scale measures
• • Justification for the scale (uses, advantages over existing measures)
• • How the preliminary pool of items was drawn up - details of sources, sampling of sources, any special steps regarding content or face validity
• • A description of the sample used for testing
• • Reliability statistics
• • Validity statistics
• • The scale itself (instructions, items or examples of items)
• • Descriptive statistics (norms): means, standard deviations, ranges (for different samples of participants, different sub-scales)

Summary

This chapter describes the final steps in presenting the scale, describing how to carry out validity testing. These put the final touches to the basic requirements of developing a scale that measures reliably what it is supposed to measure. The test should be usable by others to obtain results that can be interpreted and compared using the normative data you have produced.

Appendix 6: Computation and validity

This appendix gives instructions for carrying out statistical tests for the main types of validity, using IBM SPSS for Windows. Many of the tests are considered quite advanced, and instructions for their use have been offered in as clear and simplified a manner as possible (hopefully not over-simplified). More advice and information on the use ofinferential statistics can be obtained from a suitably qualified person, or from a competent book such as by Clark-Carter (2018), Field (2017), Gravetter and Wallnau (2016) or Pallant (2016).

Appendix 6.1: Computing total scores on your measure

Although by now you have obtained descriptive statistics (means, standard deviations and other statistics) for your measure using SPSS or other reliability, a reliability facility does not actually produce individual total scores for each participant. You need to calculate these scores in order to do the necessary statistics to establish validity.

• • With your data open in SPSS, select Transform/Compute Variable.
• • In the top left dialogue box enter a name for the new variable you are going to compute, e.g. Total.
• • Select the variables you are going to need to compute this new variable. Move each variable into the Numeric Expression box, adding after each the appropriate operator such as +. You can type these in directly, or select from the choice below the numeric expression box. For example if you wanted to compute the total score on the (hypothetical) reliable prayer scale, using items 1-5 and 7, your Numeric Expression box would contain QI + Q2 + Q3 + Q4 + Q5 + Q7.
• • OK.

A new variable, called in this hypothetical example Total, should appear in the database. Save the new version of the database.