Linear regression analysis of CFR*_{crudetimecorrected(70+)}, CFR*_{crudetimecorrected(70+)A}, and CFR*_{crudetimecorrected(0}−₆₉₎ versus percent of cases 70 years old and above (p(70+)).

A shows a plot of CFR*_{crudetimecorrected(70+)} (blue) and CFR_{crudetimecorrected(0}−₆₉₎ (green) for each country versus the percent of cases 70 years old and above (p(70+)). It is seen that for all countries the CFR_{crudetimecorrected(70)} term explains the large majority of CFR_{crudetimecorrected} (81% +/- 8%). The majority of the variance in CFR_{crudetimecorrected(70)} is explained by cases 70 years old and above (R² = 0.82). B shows a plot of CFR_{crudetimecorrected(70+A)} (blue) for each country. The value of cCFR_70+A for each country was calculated by adjusting the fraction of cases in the 70 and over group who are 80 years old and above to be 40% (p(80+)/p(70+) = 0.40), which is the mean of the countries examined (Table 3). The higher fraction of the variance explained by age for CFR_{crudetimecorrected(70+A)} (R² = 0.89) indicates that the percentage of the population 80 years and older are an important factor in determining the average population value of CFR_crude.