Powers corresponding to section 3 involving devolved authorities

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While this technique can be used to ask many questions in a short amount of space and can be intuitively appealing to most persons, it can however be tiresome if used too extensively on a questionnaire and sometimes can be difficult to label the end-points of a semantic scale.

SELF-ASSESSMENT EXERCISE 1

What are the similarities between scales and index?

Why must researchers understand levels of measurement?

59 Reliability

An instrument can be said to be reliable if it constantly gives the same answer to an issue.

According to Wimmer and Dominick (2011 p.58) reliability consists of three different components- stability, internal consistency and equivalency. Stability refers to the consistency of a result or of a measure at different points in time. Internal consistency involves examining the consistency of performance among the items that compose a scale. Equivalency sometimes referred to as cross-test reliability assesses the relative correlation between two parallel forms of a test.

“Measurements are reliable to the extent that they are repeatable and that any random influence which tends to make measurements different from occasion to occasion or circumstance to circumstance is a source of measurement error.” It is also “the degree to which a test consistently measures whatever it measures.” Errors of measurement that affect reliability are random errors and errors of measurement that affect validity are systematic or constant errors.

Validity

An instrument is valid when it measures what it is supposed to measure. There are four major types of validity- face validity, predictive validity, construct validity, and concurrent validity.

Face validity is examining the measuring instrument to see whether on the face it measures what it appears to measure. Predictive Validity also called Criterion-Oriented validity is checking a measurement instrument against some future outcome. It is when you are expecting a future performance based on the scores obtained currently by the measure, correlate the scores obtained with the performance. The later performance is called the criterion and the current score is the prediction. This is an empirical check on the value of the test – a criterion-oriented or predictive validation). For Concurrent validity the measuring instrument is checked against some present criterion (Wimmer and Dominick, 2011). It is the degree to which the scores on a test are related to the scores on another, already established, test administered at the same time, or to some other valid criterion available at the same time.

Construct validity is adjudged the most complex (Wimmer and Dominick, 2011). Construct validity is the degree to which a test measures an intended hypothetical construct. It involves relating a measuring instrument to some overall theoretical framework to ensure that the measurement is logically related to other concepts in the framework (Wimmer and Dominick, 2011 p.60). Howell et al (2012) further assert that “construct validity seeks agreement between a theoretical concept and a specific measuring device or procedure. For example, a researcher inventing a new IQ test might spend a great deal of time attempting to "define" intelligence in order to reach an acceptable level of construct validity.”

There is also content validity, and this is “based on the extent to which a measurement reflects the specific intended domain of content (Howell et al, 2012).

4.0 Conclusion

Concepts, constructs and variables must be understood in the context of the research if it must accomplish its purpose. While taking an appropriate measurement scale and instrument, it is also important that the instrument is reliable and measures what it purports to measure.

60 5.0 Summary

In this unit, you have learnt about the four levels of measurement- nominal, ordinal, interval and ratio and why it is important to understand measurement. Also the different scales of measurements used in social science research- Likert, Thurston, Guttman, Semantic differential.

6.0 Tutor-Marked Assignment

1. Develop a measurement technique to examine each of these concepts:

 Television viewing

 Newspaper reading

2. What type of data is associated with each of the following concepts:

 Beauty pageants

 Basket ball standings

 Dress size

 Time and distance

 Football jerseys

61 7.0 References/Further Readings

Tejumaiye, A. (2003). Mass Communication Research: An Introduction. Ibadan: Sceptre Prints Ltd

Wimmer, R. D. & Dominick, J. R. (2011). Mass Media Research. An Introduction. (9th Ed).

Wadsworth Cengage Learning.

Internet sources

Crossman, A. (2013). Indexes and Scales. http://sociology.about.com/od/Research-Tools/a/indexes-scales.htm.

FAO corporate document repository. (n. d). Chapter 3: Levels of Measurement and Scaling.

http://www.fao.org/docrep/W3241E/w3241e04.htm.

Howell, J., Miller, P., Park, H. H., Sattler, D., Schack, T., Spery, E., Widhalm, S. and Palmquist, M. (2012). Reliability and Validity. Writing@CSU. Colorado State University. Available at http://writing.colostate.edu/guides/guide.cfm?guideid=66.

Levels of measurement. Accessed at

http://psychology.ucdavis.edu/sommerb/sommerdemo/scaling/levels.htm

Social Research Methods/Indexes, Scales, Typologies (2010).

http://en.wikibooks.org/wiki/Social_Research_Methods/Indexes,_Scales,_Typologies.

Taylor, C. (n. d). Levels of Measurement.

http://statistics.about.com/od/HelpandTutorials/a/Levels-Of-Measurement.htm.

Trochim, W. M. K. (2006). Levels of Measurement.

http://www.socialresearchmethods.net/kb/measlevl.php. Research Methods Knowledge Base.

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MODULE 3: MAJOR COMMUNICATION RESEARCH METHODS