# Standard deviation to count

I want to calculate the standard deviation for columns called time and errors… Could someone help me? Thank you very much.

The easiest way to create two extra formula columns to calculate the `(X - Average(X))^2` part for `time` and `errors` respectively, and then calculate standard deviation as `SquareRoot(Sum(…) / Count(X))`.

See here:

P.S. “Mean” is just another word for average.

@Paul_Danyliuk
Thank you very much. Taking into account the standard deviation, I have created an indicator that informs about the impulsiveness of the person. The higher the number, the greater the impulsivity. Can you help me create a conditional formula, which will determine the color of the person depending on the intensity of impulsivity?

You can use conditional formatting to color the rows of the table. Formulas will be simple — like `Impulsiveness >= -1 AND Impulsiveness < 0`, and you can make multiple formats for different ranges and apply different colors.

If you want something else, like displaying a value in a row based on impulsiveness, you can use SwitchIf, e.g. `SwitchIf(Impulsiveness < -5, "Red", Impulsiveness < -1, "Orange", Impulsiveness < 1, "Yellow", Impulsiveness < 5, "Light green", "Green")`

Thank you, but the point is that my impulsivity index does not have a fixed scale, e.g. from 1 to 5, but it is changeable and its distribution is different depending on the sample of respondents. That is, the maximum result on the impulsivity index can be 5 in one sample but 2 in another. That means that the maximum result depends on the test sample. I do not know if I expressed myself well.

Well, you can always calculate `Min` and `Max`, and along with the average and standard deviation, use those to determine your ranges.

I believe you want something like `mean - stddev`, `mean - 2*stddev` etc, as in Bell curve?

You can also calculate each row’s rank based on the impulsiveness value, and then apply e.g. red color to the first 20% of rows, orange color to the second 20% etc.

FYI coda already has percentile functions, see: https://coda.io/formulas#Percentile and PercentileRank. But I think those don’t take stddev into account.

I don’t know what exactly you need, but given these formulas and approaches, I believe you can figure it out

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Thank you very much. I will try and do what I can to solve these issues but it is not an easy task for a novice in Coda Thank you again.