The study results indicated that NPVS-R benefitted from appropriate validity (face and content validity) and reliability, which is consistent with the results of other studies conducted on the issue [21, 31, 32]. Studies have also proved the validity of English, Spanish, Chinese, Turkish, and Korean versions of NPVS-R. Similarly, Weis and Schank (2009) assessed qualitative face validity of NPVS-R among B.Sc. and M.Sc. nursing students and clinical nurses . Considering quantitative face validity, all components showed impact scores > 1.5 in the current study and, consequently, all items were entered into the next stage that was related to content validity.
With respect to qualitative content validity in the research by Weis and Schank (2009), NPVS-R was investigated regarding sufficiency, relatedness to ethical codes, clarity, and meaning. The results revealed 100% agreement and all items were maintained with slight changes in words. That study also confirmed the content validity of the original version of this instrument .
In the present study, CVR of all components of the scale ranged from 0.6 to 1. Therefore, all components of the scale were maintained at this stage. Review of the literature showed that no studies have assessed the CVR of NPVS-R.
Our study also demonstrated that CVIs of the items and the whole scale were equal to 1. Thus, all items were accepted. In the same line, Lin and Wang evaluated content validity using CVI. In that study, seven experts including two nurses, two head nurses, one supervisor, and two assistant professors scored the Chinese version of NPVS-R with regard to relevance, clarity, and simplicity. Based on the results, CVI ranged from 0.8 to 1 and was equal to 0.9 for the final version . Geckil et al. (2012) also investigated the reliability and validity of the Turkish version of NPVS-R. The findings indicated CVIs between 0.78 and 1 for the items and 0.93 for the whole scale . Considering CVIs obtained in the present study and other studies conducted on the issue, all items of NPVS-R have acceptable validity.
With regard to construct validity in the current study, KMO was 0.93 and Bartlett’s sphericity test was statistically significant. In addition, exploratory factor analysis determined five main domains of NPVS-R by varimax rotation and exclusion of items with factor loads < 0.4. These factors included care (6 items), professionalism (7 items), activism (5 items), responsibility (4 items), and social commitment (3 items), which explained 52.26% of the total variance. It should be noted that item 17 (not participating in cares that are ethically opposed to my professional values) was excluded because its factor load was below the threshold value.
In line with the present study, Weis and Schank (2009), Geckil et al. (2012), and Moon et al. (2014) reported KMO criteria to be 0.93, 0.92, and 0.95, respectively. Bartlett’s sphericity test was also statistically significant in the above-mentioned studies (p < 0.001), which revealed appropriateness of factor analysis for construct validity of the data[21, 31, 32]. In the research by Weis and Schank (2009), the results of principal components analysis with varimax rotation and Kaiser normalization demonstrated that five factors, namely care, activism, professionalism, justice, and trust, explained 56.7% of the variance. Factor analysis also showed the high validity of the original version of the instrument . Similarly, Moon et al. (2014) investigated the Korean version of NPVS-R using factor analysis. The findings indicated that five factors explained 58.90% of the total variance and that limited cross loading existed. In that study, the instrument’s structure was somehow different from the original version, resulting in somewhat different factors; i.e., professionalism, human dignity, innovation, contribution, and advocacy. Overall, the Korean version of NPVS-R was found to be valid for assessment of nursing professional values . Geckil et al. (2012) also conducted a research on reliability and validity of the Chinese version of NPVS-R. In that study, the results of exploratory factor analysis revealed five factors; i.e., care, professionalism, trust, justice, and activism, which explained nearly 54.5% of variance . Basurto Hoyuelos (2010), too, evaluated the Spanish version of NPVS-R. The results indicated that the Spanish version was similar to the English version regarding meaning and culture and that it was appropriate for assessment of nursing professional values among nurses and students in Spain .
Based on what was mentioned above, psychometric analysis of NPVS-R has revealed the high construct validity of the instrument in various studies. Irrespective of the similar number of factors, due to differences among societies regarding cultural and social context and professional policymaking, the overall structure, subcategories, and titles of items were somewhat different from the original version.
The present study findings revealed that NPVS-R was a reliable instrument. Reliability of English, Chinese, Turkish, and Korean versions of this instrument has also been computed using Cronbach’s alpha coefficient in various studies. In the original version of the instrument, Cronbach’s alpha coefficient was 0.92 for the whole scale and ranged from 0.70 to 0.85 for the dimensions (14). Considering the Korean, Turkish, and Chinese versions, Cronbach’s alpha coefficient of the whole scale was 0.93, 0.92, and 0.90, respectively. Cronbach’s alpha coefficients of the dimensions also ranged from 0.62 to 53.89, 0.0 to 0.84, and 0.81 to 0.90, respectively [31–33] (29–31). In the same line, Lin et al. (2010) performed a study in Taiwan and reported Cronbach’s alpha coefficient of 0.90 for the whole instrument and 0.81–0.90 for its dimensions . Lakobusi et al. (2012) also reported Cronbach’s alpha coefficient of 0.93 for the whole scale .
IMPLICATIONS IN NURSING
The Persian version of NPVS-R can be used for assessment and supervision prior to interventions, evaluation and development of nursing professional values after interventions, and investigation of nursing professional values over time. Moreover, using NPVS-R can enhance nurses’ awareness about the importance of professional values and codes of ethics.