Which of the following is true about secular trend-
The term secular trend implies changes in the occurrence of disease (i.e. Progressive increase or decrease)over a long period generally several years or decades (refer page no:66 park 23 rd edition.
Road side accident is a good example
Due to environmental factors
Is due to normally occuring variation in herd immunity
Consistent change in a paicular direction over a period of time
Epidemiology