Validity

This section discusses the validity of the present study.

4.11.1 FaceValidity

Face validity is the extent to which a measure, on inspection, appears to capture the domain suggested by the relevant literature (Krippendorff, 2004). This study reused an existing measure of perceived information quality (from McKinney et al., 2002); therefore, the face validity of the measure was not solely a matter of my own judgment.

For dimensions of knowledge construction, the measure was based on definitions of the categories of explicitation and evaluation by Schellens and Valcke (2005). Thus, again, even though the measure was not reused, its face validity was to an extent supported by prior literature.

4.11.2 ContentValidity

Content validity is the extent to which a measure captures the domain of the target construct. Unlike face validity, which is subjective, content validity is an objective property of a measure. Content validity can be tested by formally surveying experts (Lawshe, 1975). An alternative way to ensure content validity is by formulating the measure based on a broad review of the literature.

In this study formal content validity checks (involving a panel of experts commenting on the items included in the measure and on the measure completeness) were not possible because of resource (primarily, time) constraints. Content validity was

addressed by relying on a broad review of the literature in formulating the items, and on reusing existing, validated measures whenever possible.

The conceptualization of knowledge construction and the measures of its dimensions was based on a broad review of literature (see section 2.6), and on a synthesis of the literature (see Table 2-18). More specifically, an existing coding scheme was used as a basis, which was selected as the measure best representing the overall body of literature on the topic of knowledge construction in online discussions.

The conceptualization of perceived information quality and the measures of its dimensions were based on the work by McKinney et al. (2002), who based their measure on a broad review of literature.

4.11.3 NomologicalValidity

Nomological validity refers to the measure being used to test well-established models and theories and confirming the relationships predicted by these models and theories. This study was to a considerable extent exploratory; hence, the measures I used were

not used in conjunction with strong, well-established theories. Therefore, nomological validity could not be asserted.

4.11.4 Construct,Convergent,andDiscriminantValidity

Construct validity refers to whether the measure does in fact measure the construct it is intended to measure. For latent constructs (constructs that cannot be measured directly, as was the case for all constructs employed in this study), construct validity cannot be assessed directly, but face validity (see section 4.11.1), content validity (see section 4.11.2), and nomological validity (see section 4.11.3) contribute to construct validity (that is, face validity, content validity, and nomological validity constitute evidence of construct validity).

Convergent validity and discriminant validity (see section 4.12) are also evidence of construct validity. Convergent validity refers to whether the measure correlates with other (presumed to be valid) measures intended to measure the same construct. Discriminant validity refers to whether the measure is sufficiently different (does not correlate too much) with the measures of other constructs included in the same model. For models involving constructs measured by multiple reflective indicators, there are established statistical procedures that can be used to confirm convergent and

discriminant validities of the measures. These procedures are introduced in section 4.12.

4.11.5 InternalValidity

Internal validity refers to whether the nature of the relationships between constructs is as hypothesized in the study. In context of this study, a major aspect of internal validity is whether cause-effect relationships hypothesized in the study refer to actual causes and effects.

This study is a correlational study, and cause-effect relationships cannot be verified directly. One can argue that the nature of this study is such that causes and effects are not likely to be mixed up. Clearly, the transcript is first created (knowledge

terms of perceived information quality and information integrity. Nonetheless, one can also argue that in asynchronous discussions contributors read the partial transcript of the discussion as they are involved in the discussion; hence information quality may be affecting the knowledge construction in the discussion.

Experiments can be used to directly and rigorously test the existence of cause-effect relationships. However, as discussed in section 4.3.4, experimental studies of

knowledge construction in online discussions are problematic because such discussions are difficult to control.

An alternative approach to clarifying cause–effect relationships is by conducting in- depth qualitative analysis. This is clearly feasible for health support group online discussions, but was beyond the scope of this study.

4.11.6 ExternalValidity(Generalizability)

External validity refers to the extent to which the results of the study can be generalized to a real-world population. This study was limited to a particular period of time and to a particular discussion forum. Therefore, one cannot claim generalizability based on how the content was sampled. On the other hand, as the forum and the content were chosen to be typical of this kind of content, one can claim analytical generalizability (Bedi & Alexander, 2009; Taber, 2000; Yin, 2009)—one can argue that if the hypothesized reasons for the relationships discovered in this study are correct, the results can be generalized to similar settings (where the same reasons apply) that were not part of the population sampled in the research.

4.11.7 EcologicalValidity

Ecological validity is the extent to which the study setting approximated a real-world setting. This study used a transcript of a real world-discussion group. Therefore, the ecological validity was high.

4.11.8 SocialValidity

Social validity refers to whether or not the research positively contributes to a public discussion of important issues.

This research directly relates to patient centred care and to the danger of Internet users acting on incorrect healthcare related information they obtain from the Internet (the literature highlighting these points was discussed in section 2.3). To ensure that the contribution of this research is positive (and thus to ensure social validity), utmost care was taken to ensure that both the implications and the limitations of this research are well understood and presented explicitly.