Statistical analysis
Normality of data was assessed via kurtosis, skewness, Q-Q plots and the
Kolmogorov-Smirnov test (with Lilliefors significance correction).
Heteroscedasticity was assessed with Levene’s inferential test. All
statistical analyses were completed using IBM’s Statistical
Package for Social Sciences (SPSS, Ver. 27.0) and included demographics,
independent
sample t-tests, Chi-square tests and ANOVA (Bonferroni post-hoc test)
were used to determine significance between groups. Multivariate
analysis was conducted to control for selected confounding variables. A
bivariate (two-tailed) Pearson correlation coefficient was used to
determine relationships between selected outcome variables. Alpha was
set a priori at P < .05 to determine significance between
groups.
Point prevalence was determined by the number of surfers or swimmers
with a AK, BCC, SCC, SCC in situ or MSC divided by those in the same
group without. The standardized rate per 100,000 was calculated as, for
example, the number of surfers or swimmer participants identified with a
particular skin cancer multiplied by 100,000 then divided by the total
number of surfers or swimmers, respectively.20 Odds ratios (OR), a
ratio of two sets of odds, were determined with scale data and
calculated as the odds of those in the exposed group (for example
surfers with a BCC) divided by all surfers. The OR of surfers to
swimmers was then determined by the odds in surfers divided by the odds
in swimmers. Comparative OR for the Australia general population were
identified within the literature.8,9,21