. 2017 Dec 5;16(Suppl 1):109. doi: 10.1186/s12940-017-0323-4

Table 1.

Advantages and disadvantages of using an excess winter mortality index to determine wintertime health burdens

Advantages:	Disadvantages:
• It is easy and quick to calculate. If daily or even seasonal mortality counts are available, the formula can be applied without advanced statistical methods. • It is readily understood by the lay public and policymakers. • It can measure the full excess at wintertime, without missing many deaths due to delayed effects.	• It is crude. Seasonal changes in health do not occur according to fixed calendar dates. • Not all deaths due to cold are during the winter, and not all of the winter excess is due to cold. • International comparisons are complicated by potential differences in the distribution of wintertime deaths and the length of the winter period. • The ratio may be sensitive to the periods used in the denominator, e.g. if summer months are included the occurrence of a heat-wave may artificially reduce the index. • It doesn’t allow for identification of which weather factors are important for health or for the specific conditions, e.g. are cold-spells occurring early in the winter worse than later ones?

Advantages:

Disadvantages:

• It is easy and quick to calculate. If daily or even seasonal mortality counts are available, the formula can be applied without advanced statistical methods.
• It is readily understood by the lay public and policymakers.
• It can measure the full excess at wintertime, without missing many deaths due to delayed effects.

• It is crude. Seasonal changes in health do not occur according to fixed calendar dates.
• Not all deaths due to cold are during the winter, and not all of the winter excess is due to cold.
• International comparisons are complicated by potential differences in the distribution of wintertime deaths and the length of the winter period.
• The ratio may be sensitive to the periods used in the denominator, e.g. if summer months are included the occurrence of a heat-wave may artificially reduce the index.
• It doesn’t allow for identification of which weather factors are important for health or for the specific conditions, e.g. are cold-spells occurring early in the winter worse than later ones?