The Way a Seasonal Index Is Computed Involves Which of the Following

Multiple Choice

The way a seasonal index is computed involves which of the following steps?

A) Remove the effect of seasonal and random variation by regression analysis.
B) For each time period,compute the ratio,which removes most of the trend variation for that time period.
C) Calculate the average of all the ratios:over all time periods to remove random variation and leaving a measure of seasonality.
D) All of these choices are true.