Table 1

Results from Classical Test Theory and Item Response Modeling Analyses of the Fruit Self-Efficacy Scales

Scale/Item

M (SD)

CITC

Factor

Est (SE)

Infit


Item stem for Fruit (N = 664): How sure are you that you can...


181

×

eat 1 portion of fruit for a snack at home at least one time?

0.82 (0.38)

0.47

0.70

-0.94 (0.07)

0.94

169

drink a glass of 100% juice or eat a piece of fruit at breakfast at least one time?

0.78 (0.40)

0.42

0.63

-0.64 (0.07)

0.97

173

×

eat 1 portion of fruit at lunch at least one time on a school day?

0.78 (0.41)

0.43

0.64

-0.63 (0.07)

1.00

197

eat 1 portion of fruit at a cafeteria place at least one time?

0.77 (0.41)

0.49

0.70

-0.56 (0.07)

0.92

165

ask someone in family to buy your favorite fruit or vegetable at least one time?

0.77 (0.41)

0.43

0.63

-0.56 (0.07)

1.02

187

×

eat 1 portion of fruit for dinner or supper at home at least one time?

0.77 (0.42)

0.43

0.63

-0.49 (0.07)

1.00

177

×

eat 1 portion of fruit for lunch at least one time on a non-school day, including weekend?

0.75 (0.43)

0.41

0.60

-0.39 (0.07)

1.01

185

ask someone in family to serve 1 fruit instead of usual dessert for dinner at least 1 time?

0.75 (0.43)

0.48

0.68

-0.36 (0.07)

0.95

182

×

eat 1 portion of fruit for a snack at home at least 4 days a week?

0.72 (0.44)

0.48

0.68

-0.22 (0.07)

0.93

174

eat 1 portion of fruit at lunch most school days?

0.71 (0.45)

0.45

0.65

-0.11 (0.07)

1.01

178

×

eat 1 portion of fruit for lunch most non-school days, including weekends?

0.69 (0.46)

0.47

0.66

-0.02 (0.07)

0.93

198

eat 1 portion of fruit most times when you eat at a cafeteria?

0.68 (0.46)

0.42

0.60

0.04 (0.32)

1.03

193

×

eat 1 portion of fruit at a fast food place at least one time?

0.67 (0.47)

0.39

0.54

0.15 (0.07)

1.04

170

drink a glass of 100% juice or eat a piece of fruit at breakfast at least 4 days a week?

0.66 (0.47)

0.47

0.66

0.17 (0.07)

0.97

167

×

ask someone in family to buy 3 fruit or vegetables at least one time?

0.66 (0.47)

0.33

0.47

0.21 (0.07)

1.12

189

eat 2 portions of fruit at least 4 days a week?

0.65 (0.48)

0.50

0.69

0.27 (0.07)

0.95

186

×

ask someone in family to serve 1 fruit instead of your usual dessert/dinner most nights?

0.64 (0.48)

0.46

0.64

0.31 (0.07)

0.98

188

eat 1 portion of fruit for dinner or supper at home most nights?

0.61 (0.48)

0.42

0.57

0.49 (0.07)

1.03

166

×

ask someone in family to buy your favorite fruit or vegetable every week?

0.59 (0.49)

0.42

0.58

0.57 (0.07)

1.06

190

eat 2 portions of fruit at least 4 days a week, even when you are stressed?

0.57 (0.49)

0.46

0.64

0.70 (0.07)

0.95

168

×

ask someone in family to buy 3 fruit or vegetables every week?

0.54 (0.49)

0.39

0.54

0.90 (0.07)

1.09

194

×

eat 1 portion of fruit most times when you eat at a fast food place?

0.50 (0.50)

0.36

0.49

1.11 (0.07)

1.11

Item stem for Vegetables (n = 659): How sure are you that you can...

183

×

ask someone in family to serve 2 vegetables for dinner at least one time?

0.71 (0.45)

0.44

0.66

-0.79 (0.07)

1.01

199

eat 1 portion of vegetables at a cafeteria at least one time?

0.69 (0.46)

0.50

0.72

-0.70 (0.07)

0.92

179

×

cut up 1 portion of vegetables and eat it with a dip for a snack at least one time?

0.67 (0.47)

0.40

0.58

-0.58 (0.07)

1.00

175

eat 1 portion of vegetables for lunch at least 1 time on non-school day, including weekend?

0.65 (0.47)

0.39

0.58

-0.46 (0.07)

1.12

171

×

eat 1 portion of vegetables at lunch at least one time on a school day?

0.63 (0.48)

0.43

0.63

-0.29 (0.07)

1.07

195

eat 1 portion of vegetables at a fast food place at least one time?

0.61 (0.48)

0.45

0.65

-0.18 (0.07)

1.05

184

×

ask someone in family to serve 2 vegetables for dinner most nights?

0.55 (0.50)

0.56

0.77

0.14 (0.07)

0.91

180

cut up 1 portion of vegetables and eat it with a dip for a snack at least 4 days a week?

0.55 (0.50)

0.39

0.56

0.15 (0.07)

1.09

176

eat 1 portion of vegetables for lunch for most non-school days, including weekends?

0.55 (0.50)

0.52

0.72

0.15 (0.07)

0.95

200

×

eat 1 portion of vegetables most times when you eat at a cafeteria?

0.52 (0.49)

0.54

0.75

0.36 (0.24)

0.97

172

eat 1 portion of vegetables at lunch at least 4 days a week at school?

0.50 (0.50)

0.53

0.73

0.44 (0.07)

0.98

191

×

eat 3 portions of vegetables at least 4 days a week?

0.50 (0.50)

0.56

0.76

0.47 (0.07)

0.91

196

×

eat 1 portion of vegetables most times when you eat at a fast food place?

0.49 (0.50)

0.50

0.70

0.49 (0.07)

1.05

192

×

eat 3 portions of vegetables at least 4 days a week, even when you are stressed?

0.44 (0.49)

0.55

0.76

0.81 (0.07)

0.95

Item stem for Water (n = 640): How sure are you that you can...

205

×

drink only water whenever you are thirsty for at least one day?

0.79 (0.40)

0.30

0.51

-0.78 (0.07)

1.10

202

drink 4 glasses or bottles of water at least 4 days a week?

0.77 (0.41)

0.50

0.82

-0.59 (0.07)

0.93

201

×

drink 4 glasses or bottles of water at least one day?

0.75 (0.43)

0.42

0.73

-0.43 (0.07)

0.94

206

×

drink only water whenever you are thirsty at least 4 days a week?

0.71 (0.45)

0.31

0.52

-0.13 (0.07)

1.10

204

×

drink 6 glasses or bottles of water at least 4 days a week?

0.60 (0.49)

0.45

0.75

0.57 (0.07)

0.96

207

drink 6 glasses or bottles of water at least 4 days a week, even when stressed?

0.59 (0.49)

0.44

0.71

0.63 (0.17)

0.99

203

×

drink 6 glasses or bottles of water at least one day?

0.57 (0.49)

0.47

0.78

0.74 (0.07)

0.98


% Variance Explained for Fruit (Factor 1/Factor 2) (38.8%/7.5%)-Cronbach's alpha/Person-separation reliability (full scale = 0.86/0.82; reduced scale = 0.75/0.74)

% Variance Explained for Vegetables (Factor 1/Factor 2) (47.1%/9.5%)-Cronbach's alpha/Person-separation reliability (full scale = 0.84/0.83; reduced scale = 0.70/0.76)

% Variance Explained for Water (Factor 1/Factor 2) (48.7%/20.3%)-Cronbach's alpha/Person-separation reliability (full scale = 0.77/0.66; reduced scale = 0.55/0.61)

Mean (M); standard deviation (SD), corrected item-total correlation (CITC); item response modeling item difficulty estimate and standard error [Est (SE)], Infit statistic (acceptable range 0.75-1.33); Self efficacy item scale: not sure (0), sure (1); "x" identifies items used in the reduced scales

Baranowski et al. International Journal of Behavioral Nutrition and Physical Activity 2010 7:25   doi:10.1186/1479-5868-7-25

Open Data