External variables 1 Theory of Planned Behaviour Outcome
Δομή Μοντέλου External variables Σχήμα 1: Theory of Planned Behaviour Outcome beliefs X Outcome evaluation Attitude towards the behaviour Normative beliefs X Motivation to comply Subjective norm Perceived likelihood of occurrence X Perceived power to control Perceived behavioural control Intention Behaviour Actual behavioural control
Πίνακας 1: Μετα-ανάλυση μετα-αναλύσεων των εφαρμογών των TRA/TPB (Conner & Sparks, 2005) Relationship κ n r+ BI-B 420 82712 0. 48 PBC-B 241 55444 0. 35 A-B 126 28495 0. 36 SN-B 122 28410 0. 16 A-BI 497 111558 0. 51 SN-BI 472 109111 0. 34 PBC-BI 386 95877 0. 43 A-SN 120 30440 0. 36 A-PBC 91 26626 0. 41 SN-PBC 91 26626 0. 26 BB-A 137 29652 0. 54 NB-SN 124 25270 0. 49 CB-PBC 18 2744 0. 52 Note: included meta-analyses: Sheppard et al. , 1988; van den Putte, 1991; Hausenblas et al. , 1997; Sheeran & Taylor, 1999; Albarracin et al. , 2001; Armitage & Conner, 2001; Hagger et al. , 2002; Trafimow et al. , 2002; Mc. Eachan et al. , 2005. BB: behavioural beliefs; NB: normative beliefs; CB: control beliefs.
Εργαλεία μέτρησης Intention to eat a healthy diet [5 -item, 7 -point scale, alpha=. 95, scoring -3 to +3 (definitely do not-definitely do]. ‘I intend to eat a healthy diet in the future’ n Attitude (mean of six semantic differential scales, scores ranging from -3 to +3, alpha=. 83, test-retest r=. 51, p<. 01) ‘my eating a healthy diet would be/is: (bad-good, harmful-beneficial, unpleasant-pleasant, unenjoyable-enjoyable, foolish-wise, unnecessary)’ n
Εργαλεία μέτρησης Subjective Norm [single item, scored -3(unlikely) to +3 (likely)] ‘people who are important to me think I should eat a healthy diet’ n Perceived Behavioural Control [6 -item, 7 -point unipolar items, scoring from +1 to +7, alpha, . 74, test-retest r=. 53, p<. 01] ‘for me to eat a healthy diet in the future is…’ (difficult-easy) ‘I am confident that if I ate a healthy diet I could keep to it’ (strongly disagree-strongly agree) n
Εργαλεία μέτρησης Behavioural beliefs (derived from pilot interviews): (7 -item, 7 point scale, scored -3 (unlikely ) to +3 (likely) ‘eating a healthy diet would…help me loose weight/help me live longer/make me feel good about myself/take time/be expensive’ n The outcomes identified in the behavioural belief questions were also evaluated [scoring from -3 (bad) to +3 (good)]. ‘being physically fitter would be…’. n n Each behavioural belief was multiplied by the corresponding outcome evaluation and these products summed
Εργαλεία μέτρησης Normative beliefs (pilot interviews): Assessed in relation to 4 referents (friends, health experts, family, workmates). Scoring -3 (unlikely) to +3 (likely) ‘my friends think I should eat a healthier diet n motivation to comply question corresponding to normative belief question [scoring -3 (strongly disagree) to +3 (strongly agree)] ‘with regard to eating, I want to do what friends think I should do’ n n Each normative belief was multiplied by the corresponding outcome evaluation and these products summed
Εργαλεία μέτρησης Control Beliefs (pilot interviews): [11 -items, scoring ranged for 1(never) to 7(frequently)] ‘lack of support from people with whom I share food’ n Power items corresponding to each control belief question ‘lack of support from whom I share food makes my eating a healthier diet…-3(unlikely) to +3(likely) n Each control belief item was multiplied with corresponding power item, and these products were summed n Behaviour: (time 2 point) 33 -item Food Frequency Questionnaire (FFQ) n
Αποτελέσματα Table 2: Means, Standard Deviations and Intercorrelations Between Study Variables [Conner & Sparks, 2005] 1 1. HB 2. IN 3. ATT 4. SN 5. PBC 6. BB 7. NB 8. CB . 37** . 16 -. 09 . 37** . 20* . 09 . 20* . 35** . 24** . 57** . 43** . 22 . 15 . 07 . 36** . 19** . 10 -. 01 . 42** . 60** . 03 . 14* . 06 . 35 . 37** . 37 2. IN 3. ATT 4. SN 5. PBC 6. BB 7. NB . 43 8. CB Mean . 10 1. 89 2. 03 1. 51 5. 14 4. 76 6. 06 -1. 59 Sd 2. 24 1. 22 0. 96 1. 66 1. 16 2. 64 6. 04 4. 93 HB: Healthy Eating Behaviour; IN: Intentions; ATT: Attitude; SN: Subjective Norm; PBC: Perceived Behavioural Control; BB: Behavioural Beliefs; NB: Normative Beliefs; CB: Control Beliefs Note: * p<. 05, ** p<. 01. For correlation with behaviour N=144, for other correlations N= 248.
Αποτελέσματα Table 3: Hierarchical Regression Analysis of Intentions onto TPB Variables [Conner & Sparks, 2005] Predictors Unstandardised β Standard error of β Standardised Β ATT 0. 132 0. 048 0. 147** SN 0. 115 0. 024 0. 237** PBC 0. 530 0. 055 0. 515** ATT: Attitude; SN: Subjective Norm; PBC: Perceived Behavioural Control Note: ** p<. 001, R 2 = 0. 40, p<. 001, F(3, 244)= 54. 1, p<. 001
Αποτελέσματα Table 4: Hierarchical Regression Analysis of Behaviour onto TPB Variables [Conner & Sparks, 2005] Predictors Unstandardised β Standard error of β Standardised Β INT 0. 400 0. 150 0. 247** PBC 0. 370 0. 142 0. 241** ATT: INT: Intention; PBC: Perceived Behavioural Control Note: ** p<. 001, R 2 = 0. 18, p<. 001, F(2, 141)= 14. 2, p<. 001
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