Methods of statistical analysis

The questionnaire data was analysed using the statistics package, SPSS version 11. The data was coded and transformed into a number of different types of variable namely nominal (binary), nominal (categorical), ordinal and scale. A selection of four different non-parametric statistical tests was used to test for the existence of statistically significant associations or cor­relations between different combinations (pairs) of variables. The rationale behind the choice of the four tests was that the most powerful and appro­priate test available should be used for any given combination of variables. Table 1 indicates which test was used for a particular combination of vari­ables.

Table 1. Statistical tests used on variable combinations

Variables

Nominal

(binary)

Nominal

(categorical)

Ordinal

Scale

Nominal

Chi-Square

Chi-Square

Mann-

Mann-

(binary)

Whitney

Whitney

Nominal

Chi-Square

Chi-Square

Kruskal-

Kruskal-

(categorical)

Wallis

Wallis

Ordinal

Mann-

Kruskal-

Spearman’s

Spearman’s

Whitney

Wallis

Correlation

Correlation

Scale

Mann-

Kruskal-

Spearman’s

Spearman’s

Whitney

Wallis

Correlation

Correlation

There were essentially three types of variables used in the study namely the independent variables (see following paragraph), the demographic variables (gender, age, occupation and educational attainment) and the de­pendent, perceptual variables representing the four research themes (more information is given about these in the thematic sections below).

Three independent variables are referred to in this paper and these are “vegetation density”, “housing density”, and “location in relation to Birchwood”. The scores for the vegetation and housing density of the 12 HCA’s were simply transformed into the scale variables “vegetation den­sity”, and “housing density”, where the values consisted of the vegetation scores and dwellings per hectare respectively. The variable “location in re­lation to Birchwood”, was a nominal (binary) variable, where the values 1 and 2 denoted whether the respondent lived in Birchwood, or in one of the three control HCA’s outside.