Table 1 Constructs, sources, validity and reliability of items used in the study

Stages of

change

One item with five options of “I currently consume less than 2 units* of dairy per day, and I do not intend to increase its consumption within the next 6 months” (pre-contemplation phase); “I currently consume less than 2 units* of dairy per day, but I plan to increase it within the next 6 months” (contemplation phase); “I currently consume less than 2 units* of dairy per day, but I plan to increase it to 2 to 3 units* per day within the next 30 days” (preparation phase); “I have been consuming 2 to 3 units* of dairy products daily for the past 6 months” (action phase); “I have been consuming 2 to 3 dairy products a day for more than 6 months” (maintenance phase)

Gulliver and Horwath [18]

1.00

1.00

1.00*

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Processes of

change

including 10 items of cognitive processes of change and 10 items of behavioral processes of change evaluated with Likert-type options from never (1 score) to ever (5 scores)

made by the authors

0.72

0.93

0.97

0.88

Decisional

balance

Including 10 items related to the pros and 12 items related to the cons of dairy consumption subscale with options of “It is not important at all” (1 score); “it is a little important” (2 scores); “it is somewhat important” (3 scores); “it is important” (4 scores); and “it is very important” (5 scores)

Gulliver and Horwath [19] and Vahedi et al. [20]; with adapt of some items

0.75

0.94

0.98

0.88

Self-efficacy

10 items with options of “I’m not sure at all” (1 score); “I’m somewhat sure” (2 scores); “I’m sure” (3 scores); “and I’m totally sure” (4 scores)

Horan et al. [21] and the Gulliver and Horwath [19]; with adapt of some items

0.89

0.99

0.98

0.88