Table 6

Factor analyses performed (n = 13).

Authors, year, country

Number of factors identified (no. of items included in the solution) Cronbach's alpha values of the factors

Variance accounted for by the factors %

Methods used

Funk et al. 1991,

USA

4 (28) in both samples 0.65-0.80

43.4 respectively 44.9

Principal Component Analysis (PCA) with varimax rotation

Shaffer, 1994, USA

Several possible solutions were identified

Not reported

Dunn et al. 1998, UK

The Funk model not appropriate

Confirmatory factor analyses (structural equation modeling)

Retsas and Nolan, 1999, Australia

3 (26)

38.9

PCA with varimax rotation

Retsas, 2000, Australia

4 (29) 0.68-0.85

46.5

PCA with varimax rotation

Marsh et al. 2001, UK

4 (27 resp 24)

The items loaded inconsistently on the four factors (two samples). Impossible to interpret the factors

PCA followed by confirmatory factor analysis

Closs and Bryar, 2001, UK

4 (23) 0.66-0.79

47.5

PCA with varimax rotation

Sommer, 2003, USA

8, 4, and 3 factors were possible solutions

Not reported

Hutchinson and Johnston, 2004, Australia

4 (27) 0.54-0.74

39.2

PCA

Kirshbaum et al. 2004, UK

3

Least squares extraction with varimax rotation

Nilsson Kajermo, 2004, Sweden

4 (27) 0.90-0.96

45.3

PCA with varimax rotation

Ashley, 2005, USA

4 (29)

Not reported

PCA with varimax rotation

Mehrdad et al. 2008, Iran

4 (31)

46.5

PCA

Kajermo et al. Implementation Science 2010 5:32   doi:10.1186/1748-5908-5-32