Test retest of overall barriers score. a. Bland Altman Line of Equality showing overall barriers score calculated from responses at time a (first administration) plotted against overall barriers score calculated at time b (two weeks later) (N = 17). b. Bland Altman plot showing mean overall barriers score against differences between the overall barriers score at time a (first administration) and b (two weeks later). The centre line represents zero (i.e., perfect agreement). The top and bottom lines represent 95% limits of agreement (mean ± 1.96SD) so that in a randomly selected respondent from the general population the difference between the two responses would be expected to lie between these limits of agreement with approximately 95% probability (N = 17).