Technically, sample size for an SEM varies depending on many factors, including fit index, model size, distribution of the variables, amount of missing data, reliability of the variables, and strength of path parameters (Fan et al. 1999; Muthen and Muthen 2002; Fritz and MacKinnon 2007; Iacobucci 2010).
Following a rigorous process of questionnaire development including forward backwards translation, the NORPEQ questionnaire was assessed for levels of missing data, reliability and validity in the four countries.
The relationships between these mode features, mediating variables, and three response quality indicators (rate of missing values, reliability, accuracy) are shown in figure 1 and have been previously described by Tourangeau and colleagues [ 9].
Although many factors including size of the model, distribution of variables, amount of missing data, reliability of the variables and strength of the relationship among variables affect the sample size [ 30], a recommended sample size for CFA is more than 5 times the number of items in the instrument [ 29].
The objective of the present study was to assess the effects of an auditory Lane Departure Warning System (LDWS) for partial and full lane departures (onset manipulation) combined with missed warnings (reliability manipulation: 100% reliable, 83% reliable and 66% reliable) on drivers' performances and acceptance.
Item missing, internal consistency reliability and construct validity.
These two aspects (limitation of missing data and reliability of the assessment) are critical in the case of small samples.
According to COSMIN checklist [ 37] and to previous PAM 13 validation studies [ 24, 26], the statistical analysis was conducted in three main steps: missing data analysis, reliability analysis, and Rasch Model analysis.
Each of the variable attribute do not add to 100% because of missing responses The reliability split half measure had a strong Cronbach alpha of 0.90 for the first three subscales on the ADL (bathing, dressing, and going to the toilet).
