Table 2.

Internal Consistency Reliability of the TFI

Authors	Internal Consistency Reliability
Gobbens et al1	Cronbach’s alpha: total 0.73, physical 0.70, psychological 0.63, social 0.34
Metzelthin et al36	Cronbach’s alpha: total 0.79 Corrected item-total correlations: correlations ranged from 0.18 to 0.58 (mean 0.39)
Gobbens et al40	Cronbach’s alpha: total 0.71, physical 0.67, psychological 0.54, social 0.51
Santiago et al7	Cronbach’s alpha: total 0.78, physical 0.79, psychological 0.53, social 0.38
Uchmanowicz et al11	Cronbach’s alpha: total 0.72 Cronbach’s alpha reliability coefficients after the removal of an item ranged from 0.68 (coping) to 0.73 (anxiety)
Mulasso et al9	Cronbach’s alpha: total 0.66, physical 0.57, psychological 0.51, social 0.36 Corrected item-total correlations for each item with the domains in general, accepted values, with some exceptions (unexplained weight loss, poor hearing)
Coelho et al10	KR-20: total 0.78, physical 0.75, psychological 0.48, social 0.49
Uchmanowicz et al50	Cronbach’s alpha: total 0.74, physical 0.72, psychological 0.37, social 0.59 Corrected item-total correlations: ranged from 0.12 to 0.55
Freitag et al12	Cronbach’s alpha: total 0.67, physical 0.66, psychological 0.43, social 0.36 Cronbach’s alpha reliability coefficients after the removal of an item ranged from 0.6 (physical tiredness)–0.69 (coping) Corrected item-total correlations ranged from 0.12 (memory problems) to 0.58 (physical tiredness)
Dong et al13	Cronbach’s alpha: total 0.71, physical 0.71, psychological 0.51, social 0.25
Renne & Gobbens45	Cronbach’s alpha: total 0.80, physical 0.74, psychological 0.61, social 0.51
Vrotsou et al14	KR-20: total 0.69, physical 0.64, psychological 0.58, social 0.22
Topcu et al15	Cronbach’s alpha: total 0.68 Cronbach’s alpha reliability coefficients after the removal of an item ranged from 0.62 (physical tiredness)–0.69 (lack of social relations)Corrected item-total correlations: ranged from −0.05 (living alone) to 0.57 (physical tiredness)
Alqahtani et al52	KR-20: total 0.70, physical 0.68, psychological 0.57, social 0.42; the KR-20 after the removal of an item ranged from 0.66 (coping)–0.72 (poor hearing, physical tiredness) Corrected item-total correlations ranged from 0.10 (unexplained weight loss) to 0.47 (coping)
Zhang et al47	Cronbach’s alpha: varied among five countries involved: total 0.70 (Spain)–0.75 (Croatia), physical 0.60 (Spain)–0.73 (The Netherlands), psychological 0.38 (UK)–0.55 (Greece, Croatia), social 0.22 (Greece)–0.43 (The Netherlands)

Abbreviation: KR-20, Kuder–Richardson formula.