Details of the methods used to develop the POS tobacco visibility tool are provided in Eadie et al.82 This text has been adapted with written permission from Tobacco Regulatory Science.
The paper by Eadie et al.82presents our approach to measuring tobacco visibility. A summary of the work is provided in this section. This has been adapted from the published paper with permission of the Tobacco Regulatory Science Group. Subsequent sections report changes in exposure to tobacco products over the DISPLAY study period using the methods that we developed.
Methods
As there was no comprehensive tool for assessing tobacco visibility, we developed a dedicated tool to assess the visibility of tobacco products and tobacco storage units. Data were collected as part of observational audits of all fixed retail outlets selling tobacco in our four study communities over a 5-year period carried out annually from February 2013 to February 2017. The data were used to compute annual visibility scores for the two dimensions of visibility: tobacco products and tobacco storage units. Full details of the methods for the observational audit and retailer panel are in Chapter 2, Tobacco advertising and marketing audits of tobacco retail outlets.
Measurement of tobacco product visibility was assessed using a 5-point categorical scale on which‘4’ represented full visibility and‘0’ represented no visibility. Assessment of storage unit visibility involved measuring five key storage characteristics: visibility of storage units at POS, proximity of storage units to traffic flows through the store, storage unit size, storage unit conspicuousness and visibility of storage units from outside the store. Storage unit visibility scores for each outlet were computed by aggregating the individual scores for all five measures (range 0–22).
In the analysis we examined changes in visibility scores by SIMD quintile and study community. These were represented graphically using plots of means and associated standard errors. We carried out multivariable regression analyses for continuous measures and used alternative non-parametric
methods for ordinal outcomes to assess whether or not observed differences remained significant after adjustment was made for other factors, such as type of store and interactions between‘time’ and ‘study community’.
Results
The scale was assessed for inter-rater reliability. There was considerable inter-rater agreement, with all measurement items exceeding the suggested 70% threshold for acceptable inter-rater agreement using the percentage approach (range 92–100%).
POS LEGISLATION IMPACT ON TOBACCO PRODUCT EXPOSURE
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Product visibility
Mean product visibility scores for all retail outlets (n= 96) fell from 3.96 [standard deviation (SD) 0.41, range 0–4] before the ban to 3.16 (SD 1.33, range 0–4) after the partial ban was implemented. It then fell further to 1.13 (SD 0.57, range 0–3) after the ban was extended to include small shops (n = 93). Table 6 shows the results of two cross-sectional Mann–Whitney U-tests that indicate that retail outlets in one of the study communities (C4) had lower product visibility than those in the other three areas and that this difference was not affected by the display ban.
Figure 2 shows the mean product visibility over time across the four study areas. There were no differences in product visibility between outlets in high-deprivation areas and those in low-deprivation areas before the display ban and no differences in product visibility scores between outlets in high- deprivation areas and those in low-deprivation areas after implementation of the comprehensive display ban.
An examination of change in product visibility scores over time by outlet type revealed that product visibility in supermarkets reduced markedly after 2013 (after the display ban in large shops came into force). However, for other retail outlet types there was a more gradual change, with grocers and petrol stations, in particular, having a wide range of product visibility scores in early 2015, before the ban was extended to include smaller outlets. This indicates that some small grocery stores and garage shops had modified their tobacco product displays before the ban was extended to include small shops.
Storage unit visibility
The mean storage unit visibility score for all outlets (n= 96) before the display ban was 15.91 (SD 1.82, range 5–19). After the ban had been implemented in supermarkets, the mean storage unit visibility score
TABLE 6 Comparison of tobacco product visibility in C4 with that in the rest of the study communities
Wave Community n Rank-sum Expected z p-value
2013 C4 19 883 921.5 2.013 0.0441
2013 C1, C2, C3 77 3773 3734.5
2017 C4 17 646 799 1.985 0.0471
2017 Rest 76 3725 3572
Average product visibility
C1 C2 C3 C4 Year Study area 0 1 2 3 4 2013 2014 2015 2016 2017
FIGURE 2 Change in average tobacco product visibility over time by study area.
DOI: 10.3310/phr08010 Public Health Research 2020 Vol. 8 No. 1
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for all outlets (n= 94) dropped slightly, to 15.52 (SD 2.52, range 5–20), and then dropped further, to 14.20 (SD 3.20, range 5–19), after the ban had been implemented fully in all shop types (n = 93). The change in storage unit visibility can be attributed largely to a reduction in the conspicuousness of storage units. Storage units that are used to display tobacco products stand out more in the shop environment when they are uncovered than do storage units in which products are concealed by shutters or covers.
Figure 3 shows the change in mean storage visibility over time across the four communities. C4 (small town, medium/low deprivation) had lower mean storage unit visibility scores than the other areas before and after the ban. Interacting time and area as a predictor had no effect, indicating that the display ban did not lessen the difference between C4 and the other areas in mean storage unit visibility. This suggests that the display bans did not eliminate shop-level urban/rural differences in tobacco storage unit visibility.
Finally, there was a marginal decline in mean storage visibility scores for most outlet types over time, with the exception of large supermarkets.
Discussion
The visibility tool was a robust and reliable means of measuring tobacco visibility and proved practical to use in a range of retail environments and shop types without causing any recognisable disruption or being detected by shopkeepers or their customers. Findings show that the Scottish POS display ban has been effective in removing products from public view, thereby reducing young people’s exposure to tobacco brands, but it has had very little influence on where tobacco products are stored or on the visibility of tobacco storage units.
The visibility tool has the potential to be used elsewhere to measure product and storage unit visibility where tobacco POS display bans are planned or have been implemented. It could also be modified to assess the visibility of tobacco displays in jurisdictions where tobacco products are sold outdoors.