Using Microsoft Excel 2010 On The Heart Disease Mortality Data Rates Versus The Total Hardness

1247 Words Aug 4th, 2016 5 Pages
3.0 Statistics

Microsoft Excel 2010 was used to create a scatter plot of the heart disease mortality data rates versus the total hardness of WTPs listed in Table 2.3.1. A linear regression using Microsoft Excel Data Analysis Package, 2010 was used to find the correlation along with the R2 value and adjusted R2 value. The R2 values represent the percent of the variance of the data explained by the fitted line. In this case, the R2 values represent the variance in heart disease rates that can be explained by the change in drinking water hardness. The adjusted R2 value is dependent on the number of points within the data. The significance of the R2 value was determined by the resulting p-values. The test was considered significant if the
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This had the effect of increasing the heart disease mortality rate from 216.68 to 425.18 per 100,000 causing the rate to be closer to the CDC’s published rate for Ohio of 388.8 (CDC, 2007-2009). The age-adjusted mortality rates were also graphed versus the total hardness of the WTPs yielding a positive correlation of 0.439. An R2 value of 0.193 was found indicating that 19.3% of the variance seen in the heart disease mortality can be explained by the hardness of the drinking water. As in the total population, the adjusted R2 value was also slightly lower at 0.165. A p-value of 0.013 made the findings significant.
The age adjustment did not significantly change the correlation or R2 value, due to the similar age demographics for each study area. A comparison of the statistics from the total population to the age-adjusted is presented in Table 4.1.

All of the WTPs in the study area reported total water hardness that ranges from moderately hard to very hard. To see if a link could be established between heart disease mortality and changes in water hardness that were found in WTPs within the same hardness classification, WTPs were broken down into 3 groups according to their total hardness; moderately hard (60-120mg/l), hard (121-180 mg/l) and very hard (>180mg/l).

Each of the classifications resulted in positive R2 values following along with the positive trend found in the initial
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