Results 2: Theoretical Relationships between Constructs 8.0 Introduction to the Chapter

Chapter 8 will commence with an exploration of the underlying factor structure of the data using Exploratory Factor Analysis (EFA). The accepted factor structure will be compared to the hypothesised Adapted TPB model (Figure 13).

Any potential changes to the structure of the constructs will be evaluated and a Confirmatory Factor Analysis (CFA) will be carried out to confirm the factor structure. SEM will then be used to determine the acceptability of the proposed model, and examine the strength of the hypothesised relationships between the constructs.

8.1 Data set

Chapter 8 will use the data collected where no intervention was present to examine the factor structure underlying food choice in leisure centres without any modifications to the food environment. This includes the data collected from both centres during the pre-intervention week (week 1), and the data collected from the control centre during the intervention week (week 2) (Table 42). These sections accumulated a total of 255 questionnaires.

Figure 13: Adapted Theory of Planned Behaviour Concern Motives

Subjective Norm

PBC Attitudes

Intention Behaviour

Confidence

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Table 42: Identification of the questionnaires included within the present section Leisure centre Week 1: Pre-intervention

(number)

Week 2: Intervention (number)

Experimental centre 66 Not included in this section

Control centre 151 38

8.2 Exploratory factor analysis

An EFA was carried out to examine the underlying factor structure within the data. The KMO value in the present study was 0.902 which greatly exceeded the cut-off point of ≥.5 (Kaiser, 1974), and is considered 'superb' (Field, 2005).

Bartlett's Measure of Sphericity was significant (p=<0.001), thus further confirming that factor analysis was appropriate for the data.

8.2.1 Decision criteria

Using Kaiser’s criteria (Kaiser, 1960; Williams, Onsman and Brown, 2010), a well used approach (Fabrigar et al., 1999), only factors with an eigenvalue > 1 were retained. Based on the sample size, only loadings > .4 on each factor were accepted (Stevens, 2002; Field, 2009). Any items loading below this cut-off point were omitted from further analysis. Items which loaded >1 or loaded onto multiple factors, with a <.1 difference between factor loadings, were also omitted from further analysis (Lee et al., 2007). Out of 40 items, 8 items were removed including: Concern about 'Gaining weight', Concern about 'Saturated fat in your food', ‘It is important to me that my diet is low in salt’, 'Even if I want to make healthy choices in the leisure centre café I do not think I would be able to do so', 'The information in the leisure centre café today helps give me control over whether I make healthy choices', Motivated to make food choices which are 'Low in salt', Motivated to make food choices which are ‘Low in sugar’ and motivated to make food choices which are ‘Low in saturated fat’. Justifications for their removal are provided in section 8.2.2.

165 8.2.2 Factor extraction

Eight factors were extracted with eigenvalues above 1. Seven of the extracted factors were retained for the analysis. The eighth factor was excluded on the basis that the majority of items either loaded below the .4 cut-off point or loaded onto another factor with <.1 difference (Lee et al., 2007). Following the removal of these items, only one item remained on factor eight which was deemed insufficient to warrant retaining the factor. The items that comprise the seven factors retained for further analysis are identified below.

8.2.2.1 Factor 1: Intention (INT)

All six of the items regarding intention loaded onto the same factor (Table 43).

All of the loadings were high, ≥.84. The Cronbach's alpha for this factor was .965 which is above the recommended value of >.7 and demonstrates good internal consistency (Pallant, 2007).

Table 43: Items and factor loadings for the Intention construct

Item Loading

How much do you agree with the following statements?

I definitely intended to make low saturated fat choices within

the leisure centre café today .994

I definitely intended to make low calorie choices within the leisure centre café today

.970 I definitely intended to make low sugar choices within the

leisure centre café today

.934

I definitely intended to make healthy choices within the leisure

centre café today .884

I definitely intended to make low fat choices within the leisure centre café today

.856 I definitely intended to make low salt choices within the leisure

centre café today .840

8.2.2.2 Concern

Items relating to the Concern construct loaded onto two factors. Concern about fat, sugar, calories and salt loaded onto Factor 2, however concern about coronary heart disease (CHD) and blood pressure (BP) loaded onto Factor 7.

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The internal consistency was good for Factor 2 (.869) and for Factor 7 (.963), suggesting that it was appropriate to consider the factors as two separate dimensions. Factor 2 was named Concern Nutrients and Factor 7 was named Concern Disease, based on the items which had loaded onto each factor. Once separated, their place in the ATPB needed to be reviewed. It was hypothesised that Concern Disease would inform Concern Nutrients. This was based on the recommendations that fat, sugar and salt intake should be limited to help in the prevention of CHD and BP (NHS Choices, 2014a). Therefore, individuals who are concerned about disease are more likely to be concerned about fat, sugar and salt in their food. Concern Nutrients has been considered in further detail below and Concern Disease is detailed in section 8.2.2.7.

8.2.2.2.1 Factor 2: Concern Nutrients (CN)

The Cronbach's alpha for Concern Nutrients (Table 44) was .869 which demonstrates good internal consistency (Pallant, 2007). Concern about 'Gaining weight' and 'Saturated fat in your food' also loaded onto this factor. The former item, however, was removed as it loaded below the cut-off point of .4 (Stevens, 2002; Field, 2009), and the latter item was removed as it loaded above 1 (section 8.2.1). Concern about ‘Gaining weight’ was originally included due to the focus on obesogenicity, and because individuals may attend leisure centres based on their motivation to lose weight (Davies, 2015). However, previous research in this field has also found weight control to be a less prominent factor (Sun, 2008). Concern about ‘saturated fat’ was expected to form part of this construct, based on public exposure to saturated fat content on food labels (Department of Health, 2013). However, total fat, which includes saturated fat, was retained in the factor and saturated fat still had a presence in the model, in the Intention and Attitudes constructs.

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Table 44: Items and factor loadings for the Concern Nutrients construct

Item Loading

"How concerned are you about the following issues?"

Fat in your food .895

Sugar in your food .799

Calories in your food .543

Salt in your food .510

Gaining Weight (excluded) .381

Saturated Fat (excluded) 1.11

"How motivated are you to make food choices that meet the following criteria?"

Saturated Fat (excluded) .363

8.2.2.3 Factor 3: Attitudes (ATT)

The Cronbach's alpha for this factor (Table 45) was .930 which demonstrates good internal consistency (Pallant, 2007). Attitude regarding ‘low salt’ loaded onto this factor and another factor, with <.1 difference between the values, so the item was removed. Attitudes towards ‘low salt’ was expected to form part of this construct, based on public exposure to salt content on food labels (Department of Health, 2013). However, salt still had a presence in the model, in the Intention and Concern Nutrients constructs.

Table 45: Items and factor loadings for the Attitudes construct

Item Loading

How much do you agree with the following statements?

It is important to me that my diet is low in calories .909 It is important to me that my diet is low in fat .891 It is important to me that my diet is low in sugar .739 I always follow a healthy and balanced diet .641 It is important to me that my diet is low in saturated fat .537 I am very particular about how healthy my diet is .525 It is important to me that my diet is low in salt (excluded) .642

168 8.2.2.4 Factor 4: PBCC

The results of the EFA posited that the 'PBC' and 'Confidence' constructs were measuring a similar dimension (Table 46), which had good internal reliability (.845) (Pallant, 2007). The theoretical basis for combining these constructs was explored. Ajzen and Madden (1986, p.457) stated that "people's behaviour is strongly influenced by their confidence and their ability to perform it". This statement brings together the notion of confidence, with the individual ability to perform a particular behaviour. PBC relates to the perceived ease or difficulty of performing a particular behaviour (Conner and Armitage, 1998), which reflects individual ability. Furthermore, greater levels of confidence in depicting nutrition labels is synonymous with greater perceived control. As a result it was deemed theoretically justifiable for Confidence and PBC to be combined to make a 6-item construct which was entitled ‘PBCC’.

Two further items which formed part of the original PBC construct were 'Even if I want to make healthy choices in the leisure centre café I do not think I would be able to do so' and 'The information in the leisure centre café today helps give me control over whether I make healthy choices'. The factor analysis indicated that neither of these items formed part of a construct as they did not load above the cut-off point on any factor. As a result both items were removed from this stage of the analysis. Although the former item was removed completely, the latter item, named ‘PBC, based on the information provided’ will be considered within Chapter 10, as explained in Chapter 7.

Table 46: Items and factor loadings for the PBCC construct

Item Loading

How confident do you feel about the following?

Determining if a food product would be healthy .925 Having knowledge of healthy eating guidelines .873 Understanding terminology on nutrition labels (e.g. Calories) .828 Understanding colours on nutrition labelling

(red/amber/green)

.657

How much do you agree with the following statements?

Whether I choose to make healthy choices in the leisure

centre café is entirely up to me .451

169

Item Loading

How much do you agree with the following statements?

I have control over whether I choose to make healthy choices in the leisure centre café

.416

8.2.2.5 Factor 5: Subjective Norms (SN)

All four items regarding Subjective Norms (Table 47) loaded highly onto the same factor (≥.77). The Cronbach's alpha demonstrated good internal consistency (.938) (Pallant, 2007).

Table 47: Items and factor loadings for the Subjective Norms construct

Item Loading

How much do you agree with the following statements?

My family think I should make healthy choices in the leisure centre café

.954 My friends think I should make healthy choices in the leisure

centre café .901

People who are important to me think I should make healthy choices in the leisure centre café

.873 People who influence my buying behaviour think I should

make healthy choices in the leisure centre café

.772

8.2.2.6 Factor 6: Motives (MOT)

The Cronbach's alpha for this factor (Table 48) was .846 which demonstrates good internal consistency (Pallant, 2007). Motivation to make food choices that are 'Low in sugar' and 'Low in saturated fat' loaded onto this factor and onto an additional factor with <.1 difference, and were therefore excluded. Saturated fat was expected to form part of this construct, based on public exposure to saturated fat content on food labels (Department of Health, 2013). However, saturated fat still had a presence in the model, in the Intention and Attitude constructs. In addition to loading onto two factors with <.1 difference, ‘Low in sugar’ also loaded onto the Motive factor <.4. Public interest in sugar became more prominent about two months after data collection was completed following the release of the sugar reduction report published by Public Health England (2015a). This prompted a proliferation in media interest in sugar, which

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maximised exposure of the topic in a public domain (The Guardian, 2015; NHS Choices, 2015a). The greater awareness of sugar could have led to this item loading more clearly onto the Motive construct. Although sugar was removed from the Motive construct it still had a place in the model, in the Intention, Concern Nutrients and Attitude constructs.

Motivation to make food choices that are 'Low in salt' was the only item which originally comprised the 'Motive' construct which did not load onto the factor.

This item did however load onto Factor 8, however this factor was excluded completely as it was problematic and only comprised of this single item.

However, salt still had a presence in the model, in the Intention and Concern Nutrient constructs.

Table 48: Items and factor loadings for the Motives construct

Item Loading

How motivated are you to make food choices that meet the following criteria?

Low in Calories .832

Low in Fat .774

High in protein .619

Helps me lead a healthy lifestyle .574

Cheap .506

Low in saturated fat (excluded) .429

Low in sugar (excluded) .330

8.2.2.7 Factor 7: Concern Disease (CD)

The second factor relating to concern included items relating to concern about getting CHD and high BP, and was therefore named Concern Disease (Table 49). High BP is linked with the onset of CHD, which may offer an explanation for the two items loading relatively strongly together onto the same dimension (NHS Choices, 2014a). Although a minimum of three items is usually deemed desirable for a single construct (Iacobucci, 2010), both of the items loaded highly onto this factor; ≥.86. Furthermore, the Cronbach's alpha was .963 which demonstrated very good internal consistency (Pallant, 2007).

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Table 49: Items and factor loadings for the Concern Disease construct

Item Loading

"How concerned are you about the following issues?"

Risk of high blood pressure .905

Risk of coronary heart disease .858

8.3 Adapted TPB model

In support of the ATPB model, it was evident from the EFA that each item largely loaded onto the factor that it was intended to measure. However the results of the EFA also suggested changes to the structure of Concern, PBC, and Confidence. Concern was separated into Concern Disease and Concern Nutrients, and it was hypothesised that the former would inform the latter. PBC and Confidence were combined to make PBCC (Figure 14).

Figure 14: Re-structured Adapted Theory of Planned Behaviour (ATPB) Concern

Nutrients Motives

Subjective Norms

PBCC