Table 1 Summary of the data fields generated by the spatial scan statistic for categorical HRQoL data
From: A spatial analysis of functional outcomes and quality of life outcomes after pediatric injury
Field | Name | Summary |
|---|---|---|
1 | Cluster | Unique identifier assigned to each cluster. ID is re-generated for each cluster analysis. |
2 | Categories | HRQoL response categoriy groupings determined from the data. Category 1 = very low HRQoL, 2 = low HRQoL, 3 = high HRQoL, 4 = very high HRQoL. Although the purpose of the spatial scan statistic is to detect clusters with high rates or low rates of specific outcomes, this does not necessarily mean that the detected clusters will also produce an outcome pattern in a linearly high or low manner. For example, it is possible for a cluster to be significant with a high rate of low HRQoL scores (value = 1) compared to HRQoL scores of 2, 3, or 4. It is also possible for a cluster to contain a significantly high concentration of scores equal to 1 compared to scores of 2 and 3 combined. |
3 | Observed | The number of instances an HRQoL response category was observed. |
4 | Expected | The number of instances an HRQoL response category was expected. Expected observations derived from the size of the scanning window. |
5 | RR | Relative risk (RR) attributed to each data category. RR scores provide a convenient single number summary of the direction and magnitude of the HRQoL groupings. Areas that generate statistically significant RR scores greater than one map the geographic locations where poor (or conversely, good) patient outcomes have clustered whereas areas that generate statistically significant RR scores less than one map those areas where there is a decreased risk of either a good or poor outcome. |
6 | p-value | The statistical significance of the spatial cluster (95%) |
7 | CTs in cluster | The number of census tracts (CTs) contained within the cluster. Counts of populations within each CT can be obtained by summarizing the scores generated in field 3. |
8 | Radius (km) | The search radius of the scanning window. |
9 | Time Period | The space-time scan statistic indicates at what time period the spatial cluster was evident. |