Table 2

Strength of associations (φ coefficients and corresponding p-values) between reason to use and type of supplements used (all athletes who use supplements n = 520)

No time preparing meal

Avoid sickness

Over-come injury

Doctors' advice

Iron

φ = .059

φ = .152

φ = .026

φ = .259

p = .180

p < .001

p = .554

p < .001

Ginseng

φ = .121

φ = .038

φ = .079

φ = -.088

p = .006

p = .394

p = .072

p = .044

Multi Vitamin

φ = .132

φ = .111

φ = .043

φ = -.006

p = .003

p = .011

p = .325

p = .812

Vitamin C

φ = .014

φ = .324

φ = -.005

φ = .003

p = .747

p < .001

p = .912

p = .944

Magnesium

φ = .044

φ = -.016

φ = .116

φ = .060

p = .260

p = .708

p = .008

p = .170

Echinacea

φ = .048

φ = .278

φ = .039

φ = .002

p = .272

p < .001

p = .369

p = .959

* Statistically significant φ coefficients (at p ≤ .001) are in bold and associations are categorized as strong (φ > .7), intermediate (7 <φ > .3) and weak (φ < .3).

Petróczi et al. Nutrition Journal 2007 6:34   doi:10.1186/1475-2891-6-34