Dear Irshad

Regarding the reliability:

1. The reliability measures could be developed for the whole questionnaire or for each dimension of the questionnaire . In fact, reliability consists of several measures:

2. Item alpha reliability and split-half reliability assess the internal consistency of the items in a questionnaire – that is, do the items tend to be measuring much the same thing?

3.Split-half reliability on SPSS refers to the correlation between scores based on the first half of items you list for inclusion and the second half of the items. This correlation can be adjusted statistically to maintain the original questionnaire length.

4.Coefficient alpha is merely the average of all possible split-half reliabilities for the questionnaire and so may be preferred, as it is not dependent on how the items are ordered. Coefficient alpha can be used as a means of shortening a questionnaire while maintaining or improving its internal reliability.

5. Inter-rater reliability (here assessed by kappa) is essentially a measure of agreement between the ratings of two different raters. Thus it is particularly useful for assessing codings or ratings by 'experts' of aspects of open-ended data; in other words, the quantification of qualitative data. It involves the extent of exact agreement between raters on their ratings compared with the agreement that would be expected by chance.

Note then that it is different from the correlation between raters, which does not require exact agreement to achieve high correlations but merely that the ratings agree relatively for both raters.

to be continued

Regarding Validity:

6.The concept of validity is best understood and examined within the context of its four discrete facets: content validity, construct validity, criterion validity and consequential validity.

7.Several authors suggest employing the following four steps to effectively evaluate content validity: 1) identify and outline the domain of interest, 2) gather resident domain experts, 3) develop consistent matching methodology, and 4) analyze results from the matching task.

8.Several series of steps in which to follow when pursuing a construct validation study: 1) generate hypotheses of how the construct should relate to both other constructs of interest and relevant group differences, 2) choose a measure that adequately represents the construct of interest, 3) pursue empirical study to examine the relationships hypothesized, and 4) analyze gathered data to check hypothesized relationships and to assess whether or not alternative hypotheses could explain the relationships found between the variables.

9.Criterion validity refers to the ability to draw accurate inferences from test scores to a related behavioral criterion of interest. This validity measure can be pursued in one of two contexts: predictive validity or concurrent validity. In predictive validity, researchers are interested in assessing the predictive utility of an instrument.

Regards.

Dear Irshad

One of my papers on reliability and validity is given below and it is available in my page, and it may be useful for you,

Z. A. Al-Hemyari and A. M. Al-Sarmi (2016). Validity and Reliability of Students and Academic Staff’s Surveys to Improve Higher Education. Educational Alternatives, Journal of International Scientific Publications, Vol.14, pp. 242-263.

Regards,

Zuhair