Hourly Standard Deviation

[n8str8]

I posted this in the probability forum. But I think it will get better response here.

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Hello all,

I am trying to calculate the hourly SD for my live play. I have a spreadsheet with sufficient data in the format of session win or loss ($) and session length (hours). Excel can quickly calculate SD for a range for me. However I dont know how correctly to convert it to SD/hour.

I came up with 4 possible candidates. Not sure which one (if either) is right.

1) SD/hour = SD(session win or loss) / SD(session length)

2) SD/hour = SD(session win or loss) / Avg(session length)

3) SD/hour = SD(session win or loss / session length)

4) SD/hour = SD(session win or loss / sqrt(session length))

How do I correctly calculate SD/hour from my data?

Appreciate all the help.

Thanks,
n8str8.