The present study sought to evaluate the dimensionality and structure of the PPEQ developed by Consorti et al. . Research by the current authors has previously identified the need to explore the properties of the questionnaire to provide evidence for its ongoing use as a PPE evaluation tool . Consorti et al.  calculated a total score for the PPEQ and used this score as part of their analyses in Italian medical and osteopathy students. However, Mokken scale analysis of the full 16-item PPEQ suggested that the calculation of a total score for the PPEQ is not valid in an Australian osteopathy student population.
Consorti et al.  used a Principal Components Analysis (PCA) to evaluate the internal structure of the PPEQ. Wismeijer et al.  suggest the use of a number of analytic approaches, including Mokken scale analysis, as a complementary data analysis approach to evaluate dimensionality and different levels of an underlying latent construct given this information is not obtainable from a PCA. Consorti et al.  identified a 3-component structure for the PPE in their study (‘appropriateness and usefulness’, ‘sexual implications’ and ‘passive role’) however the same structure was not identified in the present study. Through the Mokken scale analysis, three Mokken scales were identified in the present study: ‘comfort’, ‘concern’, and ‘professionalism and education’. The present study provides evidence for an alternative psychometric structure for the PPEQ that comprises three unidimensional subscales where the summed score for each subscale represents the respective latent construct. This alternative structure has similarities with the a-priori domains of ‘comfort with PPE’, and ‘professionalism, appropriateness, and perceived value’ of PPE as described by Chang and Power . Given the similarities, it may be that these are two key themes in the evaluation of PPE.
To create the three PPEQ subscales, it is suggested that item 12 be removed as it did not fit into any of the three Mokken scales identified in the analysis. This item, ‘It is inappropriate to perform PPE on persons that will be my future colleagues’, does not appear to measure a construct consistent with the other PPEQ items. The use of the term ‘inappropriate’ may account for this as it is the only item with this term. More frequently used terms in the PPEQ are ‘comfortable’, ‘concerned’ and ‘embarrassed’. Further, students in the present study may ascribe a different meaning to the term ‘inappropriate’. Students in the present study completed the PPEQ on their first day before they had participated in a practical skills class. Their frame of reference for what constitutes ‘inappropriate’ is likely to be different from other students. Another possibility is the translation of the term to ‘inappropriate’ from the initial validation study with Italian osteopathy and medical students . While the item may have had a particular meaning in the initial study, its meaning within the context of the item has been lost.
‘Comfort’ with PPE needs to be evaluated as students are often expected to participate in such activities during their pre-professional program [7, 40]. This subscale consisted of items 1–4 and 8–11. Items 1 to 4 gauge the students’ perception with regard to performance of PPE and exposure of their body. Students appear to be generally comfortable with participating in PPE [12, 39]. Items 8 to 11 specifically address comfort with PPE based on sex. The literature suggests that gender has a significant influence on student perceptions of PPE. Discomfort with examining students of a different gender has been identified by females due to fear of sexual exploitation, but also by males for fear of accusations of harassment . Students’ perceptions of these issues are likely to be captured in this PPEQ subscale. Given the increasing awareness of gender diversity it may be that these concerns are not limited to different gender interactions. This has yet to be considered in the literature and provides an avenue for further research. The ‘comfort’ subscale is the strongest of the three PPEQ subscales from a scalability and item ordering standpoint. This suggests that the comfort subscale could potentially measure changes in a students’ perception of comfort with PPE over a period of time.
Much of the literature on PPE relates to concern about participating in such activities. The focus of the PPEQ items in this subscale relates specifically to ‘sexual interest’ from not only other students but also the academic and clinical teaching staff. Female students have been reported to be more likely than males to fear critical and teasing comments, and sexual objectification . As highlighted in the discussion of the ‘comfort’ subscale, it may be that this unease extends beyond the reported female/male interaction, however such an assertion has not been described in the literature. Concern has also been expressed about the “immaturity” of fellow students and about potential sexual harassment . Wearn et al.  also suggest that issues may arise where students may be (or have previously been) close friends, housemates, or a sexual partner of their peer examiner/examinee, and therefore have blurred boundaries within the context of PPE. From a psychometric standpoint, the item ordering value (HT) was low suggesting that the ability to discern between different levels of perceived concern associated with PPE is negligible albeit a total score can be calculated for this subscale.
‘Professionalism and education’ subscale
‘Professionalism and education’ are key components in the evaluation of PPE, a position supported by the inclusion of this domain in the study by Chang & Power . Setting professional behaviour standards , undertaking a formal PPE participation consent process  and creating a positive education environment may contribute to a positive perception of PPE . This subscale also captures the students perceptions about the need to participate in PPE, a theme consistent with other work . As with the ‘concern’ subscale, the item ordering value was low suggesting that the ability to discern between different levels of perceived professionalism and education associated with PPE is negligible. This assertion is potentially supported by Vaughan & Grace  who reported no difference in perception of first year osteopathy students in the 4 items of the PPEQ making up this scale over a 12-week period. Evidence is provided for the calculation of a sum score for the subscale.
All three PPEQ subscales demonstrated high scalability coefficients suggesting they are unidimensional and the present study provides support for the their measurement of the underlying latent constructs, namely, ‘comfort’, ‘concern’, and ‘professionalism and education’ associated with PPE. For all three subscales the ωt values were approximately 0.90 suggesting that 90% of the variance in the total score for each subscale is accounted for by the respective latent construct. Calculation of a total score for each subscale (after rescoring where required) is supported by the high ωh values . This subscale score calculation is at odds with Consorti et al.  who calculated a total score for the PPEQ and such a position is not supported by the data in the current study.
There are a number of limitations in the present study. First, the study only explored the opinions of students in two Australian osteopathy programs. Therefore the generalisability of these results to other osteopathy programs, and other health professions is limited. Another limitation is that the study did not evaluate whether the structure of the questionnaire was different with different cultural groups. Acceptance and potentially participation in PPE is known to vary with different cultures  and this could result in a different questionnaire structure. It is also possible that a degree of bias was introduced with approximately three-quarters of the data in the present study obtained from one institution.
Future research and questionnaire use
The PPEQ as described in the current study has a number of uses both in the classroom and research settings. The questionnaire has the potential to be used as an evaluation of the learning environment to identify systemic concerns with participating in PPE beyond the individual student level. Systemic concerns could be addressed using Grace et al.’s  strategies for improving the experience of PPE, including the use of written consent forms and formal feedback. The PPEQ can also be used as part of a formal feedback strategy that could be used to inform educators about changes that can be made to improve or modify the PPE experience. The PPEQ also has the potential to be used in longitudinal evaluations of PPE experiences to evaluate changes in perception over time, particularly where students are participating in PPE on a regular basis. Grace et al.  suggest that “…providing students with written information about what to expect, and about the pedagogical benefits of experiential learning [PPE], and discussing ethical issues that could be associated with experiential learning could be readily implemented in practical classes” (p. 29). The PPEQ could be used to evaluate perceptions about PPE before and after the provision of this information.
The influence of gender diversity and sexuality as factors influencing PPE participation is an avenue for further research given the literature has thus far only considered female/male interactions. Further work could also explore whether the PPEQ measurement properties are retained in different cultural and gender diverse populations.