My end goal is to present the average travel time for a corridor and the standard deviation (or standard error) of that travel time. I'm not sure what to present to be statistically correct, here is the information I have to summarize:
I have the average travel time for a segment of road for a specific window of time each day of the week (say, segment A to B from 5:00 to 6:00 pm, I also have this information from B to C and C to D, etc.). I have 12 weeks of data so I basically have 60 data points for each segment (weekdays only). My first thought was to present the average and standard deviation, but then I realized I am presenting an average of averages so my standard deviation should probably be a standard error.
My problem is, in some areas I have multiple segments of road that I need to sum up and present the total average travel time (So I have 60 average travel times for A to B and 60 Average travel times for B to C, but in some areas of town I need to present the average travel time from A to C or A to D, etc.). Would it be wrong to present standard deviations of everything (including those areas of town where I am just presenting A to B), even though my data points are averages? If I am to present the standard error, and I am adding multiple segments, would my "n" just be the average of the n's in each segment? [assuming SE=SD/sqrt(n) is the correct equation to use for standard error]
This post seemed very relevant: How to 'sum' a standard deviation?, but I was worried that my situation may be different because I need to present the "A to D" information in some areas.
Hopefully I presented that clearly enough, it's a challenge to describe. Any insight will be greatly appreciated!