M.Com. (Industrial Psychology) / This study was conducted to examine the dimensionality of the Neuroticism scale of the Basic Traits Inventory in order to contribute to the larger project of developing computer adaptive testing for the five scales of the Basic Traits Inventory. The Neuroticism scale comprises the general factor of Neuroticism and four group factors or facets, namely, Affective Instability, Depression, Self-Consciousness, and Anxiety (Taylor & De Bruin, 2006; Taylor & De Bruin, 2013). Personality constructs and scales are complex as they typically comprise heterogeneous items for reliability and validity purposes (Reise, Morizot, & Hays, 2007). It is therefore to be expected that some studies present evidence of a scale that measures an overarching single dimension – unidimensionality – whilst other studies find evidence of multiple dimensions – multidimensionality (Gibbons et al., 2007; Immekus & Imbrie, 2008; Reise, Moore, & Haviland, 2010). Consequently, specification of a strictly unidimensional model is often not realistic for complex personality constructs and scales. However, test-developers and researchers aspire to unidimensionality (Zinbarg, Yovel, Revelle, & McDonald, 2006) as unidimensionality allows for the unambiguous interpretation of scale scores (Reise et al., 2010), is considered a precondition to reliability and validity, encourages the use of a total score (Netemeyer, Bearden, & Sharma, 2003), meets the unidimensional assumption of item response theory models, and is the prerequisite for the development of computer adaptive testing (Thomas, 1990; Weiss & Gibbons, 2007). Against this background, the key question that was posed in this study was not whether the Neuroticism scale was strictly unidimensional or not, but rather if the scale was unidimensional enough to allow for the meaningful interpretation of a total score (Morizot, Ainsworth, & Reise, 2009). This study focussed on attaining evidence of the presence of a strong general factor which would justify the interpretation of a total score and for applying unidimensional item response theory models to the scale (Reise, 2012). The Basic Traits Inventory was completed by 1 966 participants from various industries and organisations within South Africa. Statistical analyses were performed on the responses to the Neuroticism scale. Confirmatory factor analysis was used to investigate the unidimensionality and strength of the general factor of the scale, while evaluating the influence of multidimensionality on the interpretation of the general factor or the total score. This dimensionality investigation of the scale was achieved by comparing three confirmatory factor models using the goodness-of-fit indices and the standardised factor loadings of the models. The competing structural models were: a one-factor or unidimensional model which represented the general factor and interpretation of a total score for the scale; a four-factor or multidimensional model which represented the multiple factors of the scale and therefore the interpretation of the group factors or facets; and a bifactor model which allowed for the examination of the strength of the general factor in comparison to that of the group factors of the scale. The results of this study confirmed that the Neuroticism scale is multidimensional as the scale comprises multiple group factors or facets. However, the findings of the study revealed the strong presence of a general factor that runs through all the items of the scale, and consequently suggest that efforts to make use of and interpret separate subscale scores lack the needed empirical evidence to do so. In essence, the findings of the study demonstrated that the presence of unidimensionality in the scale is prominent despite the multidimensionality of the scale, which confirmed that the interpretation of the total score for the scale is justified and preferred irrespective of the multidimensionality of the scale. Overall, the findings and evidence of this study proposed that the Neuroticism scale is unidimensional enough to meet the unidimensional assumption of item response theory models. Accordingly, these results support the advancement of adapting the Neuroticism scale of the Basic Traits Inventory for computer adaptive testing (Reise, 2012; Thomas, 1990; Weiss & Gibbons, 2007). This study further confirmed that when developing a multifaceted scale, it is essential to analyse the dimensionality of the scale in order to determine what the scale is actually measuring. The bifactor model can be employed in the development, exploration and confirmation of the dimensionality of the scale to examine the strength of the general factor relative to the multiple group factors of the scale.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:11549 |
| Date | 19 June 2014 |
| Creators | Clifton, Sebastian |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Johannesburg |
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