Which of the following is true about secular trend-: (A) Road side accident is a good example, (B) Due to environmental factors, (C) Is due to normally occuring variation in herd immunity, (D) Consistent change in a paicular direction over a period of time
Answer is D. 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.