Hi
I want to analyse 2 periods of traffic volumes (in excel). I am hoping to confirm the best methods.
At present, I have taken the variance from the previous year comparable period (=SQRT((year 2 February volume - year 1 February volume)^2) for each of the 12 periods in the year. I have then taken the mean - this gives me the average movement on last year, accounting for seasonality.
I have then calculated the standard deviation of this mean population, highlighting data points that fall outside of the standard dev
Should I have added the last year period to current year period then taken the average of those amounts, to get the mean to use for calculating the standard dev
Not sure on the most statistically 'sound' method.
I want to analyse 2 periods of traffic volumes (in excel). I am hoping to confirm the best methods.
At present, I have taken the variance from the previous year comparable period (=SQRT((year 2 February volume - year 1 February volume)^2) for each of the 12 periods in the year. I have then taken the mean - this gives me the average movement on last year, accounting for seasonality.
I have then calculated the standard deviation of this mean population, highlighting data points that fall outside of the standard dev
Should I have added the last year period to current year period then taken the average of those amounts, to get the mean to use for calculating the standard dev
Not sure on the most statistically 'sound' method.
