Reliability and Validity in Research Reliability

Reliability is a term used to talk about the "test-retest" quality of a measurement. Reliability refers the capacity of a measurement to obtain the same results over many repetitions when all the underlying conditions are stable (Chisnall, 2005; Saunders, Lewis and Thornhill, 2009). Many research variables can change over time, and these variables can impact reliability. However, statistical procedures exist to correct for most of those changes and to allow reliable data to be collected.

Reliability of the questionnaires

Of the three options for establishing reliability (equivalent forms, internal consistency, parallel forms, and test-retest), internal consistency offers the most practical application for a survey to be used for concept testing or a product launch (Mitchell, 1996). To implement a strategy for determining internal consistency, a market researcher designs a number of survey questionnaire items that measure the same construct (idea, phenomenon, thing) (Chisnall, 2005). These similar question items will provide insight into the reliability of that particular survey instrument. Internal consistency is reflected by the degree to which the people taking...

For that matter, a pilot test of the survey questionnaire can be used to support internal validity in much the same way. The advantage of the pilot test is that it affords an opportunity to correct ambiguous questions or question items that do not demonstrate internal consistency when it was thought that they would do so.
2.0 Validity

Validity is the extent to which a test measures what it claims to measure (Cooper & Schindler, 2008; Brandly, 2010; McDaniel and Gates, 2013; Saunders, Lewis & Thornhill, 2007). It is vital for a test to be valid in order for the results to be accurately applied and interpreted. There are three different types of validity: 1) Content validity, 2) criterion-related validity, and 3) construct validity. Each of these validity types is addressed below in reference to survey questionnaire development and administration.

2.2 Validity of the questionnaires

Content validity demonstrates that questionnaire covers an adequate span…