For EFA, 184 administrative employees from Universiti Malaysia Sarawak (UNIMAS) (who were participants of CPR and AED workshops), responded to the questionnaire. Healthcare employees such as doctors, nurses and paramedic staff were excluded from this study. The mean age of the participants was 37.6 years (standard deviations +/- 6.85); and 100 of them (54.3%) were male participants. The number of participants who responded exceeded the estimated sample size according to Costello & Osborne (2005) (i.e., minimum of 5 responses per item) . As there were 22 items to be validated, the estimated sample size was 110 participants. For CFA, 100 medical doctors from the emergency department of Sarawak General Hospital (age range from 28 years to 32 years old) and 122 final year medical students from UNIMAS (age range from 23 to 25 years old) and who had been trained in CPR and AED, responded to the questionnaire. Convenient sampling was applied in recruiting the participants.
The EFA was performed in SPSS software using principal axis factoring as the extraction method. For CFA, reflective measurement modelling using partial least square was performed using SMART-PLS software. For translation of the questionnaire from English language into the local Malay language, the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) principles of good translation practice for cultural adaption was adopted as the working framework . According to the ISPOR principles, a good translation has the following steps: (1) forward translation, (2) reconciliation (3) backward translation (4) harmonization . In the forward translation stage, two authors who are fluent in both English and Malay language (SYL, DNK) independently translated the questionnaire into Malay language. After completion of the initial Malay language translation, these 2 authors of this paper then discussed and resolved any discrepancy of the translations (reconciliation). Subsequently, an independent language expert who is fluent in both languages were invited to translate the Malay language version back to English language (backward translation). Finally the original English version and the backward English version would be compared to check for significant discrepancy (“harmonization”).
Ethical approval was obtained from the Medical Research and Ethics Committee, Ministry Of Health Malaysia and the study was registered under the Malaysian National Medical Research Register (NMRR, website URL: www.nmrr.gov.my) with the research number of NMRR-16-696-39041. Written informed consent was obtained from all participants prior to their participation in this study.
With regards to the development and construct validation of the questionnaire, a preliminary version of the checklist was first constructed based on previous works [1, 3-9, 12] as well as opinions from four authors of this paper (KSC, SYL, NS and DNK). A modified Delphi method via iterative email communications and face-to-face discussion sessions were conducted. The purpose of these discussions was to come up with a list of the pertinent items purported to measure (1) the perception of the importance of bystander CPR and public access AED, (2) the perception of the confidence and willingness of bystanders to apply these two lifesaving interventions as well as (3) fears and concerns of bystander that may deter their willingness and (4) the perception of the placement strategies of these AED.
Once the preliminary list of items was determined, the participants were asked to rank the items in a Likert scale of four, ranging from “1 = strongly disagree” to “4 = strongly agree”. An initial run of EFA was performed in order to determine the number of factors to be fixed (eigenvalue>1). After fixing the number of factors, re-run of EFA was then performed to determine the factor loadings of the items as well as to identify items that may need to be removed. Promax oblique rotation was again used. In the pattern matrix, factor loading with cut-off value of <0.4 was used as the criteria to determine whether an item was to be removed or not . The communality value, which indicates convergent validity of the items, was set at 0.25. Finally, the Cronbach’s alpha coefficients (with >0.6 cut-off value) were then checked to evaluate the degree of internal consistency of the items in each construct or factor. .
With regards to CFA, convergent validity, internal consistency, and discriminant validity were determined using partial least square (PLS). For internal consistency, the composite reliability was determined, whereas for convergent validity, factor loadings and average variance extracted (AVE) were determined . In this regard, factor loading of >0.70 is used as the cut-off point; whereas for item with factor loading between 0.4 to 0,7, the effect of its removal on the overall AVE would be considered. If the removal of the item improves the AVE of the factor, the item would be removed unless the item is a priori determined by the authors to be of critical importance in terms of content validity [14, 15].
With regards to the translation process, two of the authors of this paper (SYL, DNK) independently translated the original English version into the targeted Malay language (“forward translation”) version. These two authors are proficient in both English language and Malay language. SYL is a medical doctor working in the emergency department of Sarawak General Hospital while DNK is a nursing educator from UNIMAS. These 2 authors then compared their versions of the translation with the aim of merging their versions into a single forward translation version (“reconciliation” stage). The backward translation was performed by an independent translator who is proficient in both English and Malay languages and who has vast experience in doing journalistic translation work in two languages. After completion of the backward translation, three authors (SYL, DNK, NS and KSC) then compared the back translated English version with the original English version to check for significant discrepancy (“harmonization”). Any significant discrepancy would be discussed, and revised if deemed necessary. In the unlikely event where there is discrepancy in which the authors could not amicably resolve, an independent language expert who is fluent in both English and Malay languages would be called in.