Trend surface models could adequately explain the variation in the number of HFMD cases. All models (Appendix 1 and 2) were listed as the residuals that are not spatially autocorrelated except for TS 4 for 2012. Therefore, we can choose the best model among all to represent the number of HFMD cases in Sarawak for preferred locations.
Based on Table 1, TS 1 is suggested as the best for year 2011 and TS 3 for year 2012 since it has the smallest variance of the residuals. Thus, we believe that these models could fit the number of HFMD cases data with a higher degree of reliability. Location coordinates were the only explanatory variables used in this study. More regressor variables should be used to make a better model.