# Standard deviation

#### kjebr

##### New Member
Hi, I'm trying to calculate the standard deviation of a dataset for my uni meta analysis from this formula. How would I go about calculating the inverse of phi Φ? Would I just substitute 1.618033 which is what the value of phi is according to google?

#### kjebr

##### New Member
Hi, I'm trying to calculate the standard deviation of a dataset for my uni meta analysis from this formula. How would I go about calculating the inverse of phi Φ? Would I just substitute 1.618033 which is what the value of phi is according to google?
View attachment 4083
Also b = minimum value of range
a = maximum value
n = number of participants

#### hlsmith

##### Less is more. Stay pure. Stay poor.
Curious where you are getting this formula from. Can you provide a link, so we can see how it was presented. I am not imagining phi is a constant or irrational number you are supposed to input, I feel like it may be derived from your data.

#### hlsmith

##### Less is more. Stay pure. Stay poor.
perhaps feed bracket data into norminv distribution? But if you provided content info that would help.

#### hlsmith

##### Less is more. Stay pure. Stay poor.
?
Φ symbol represents the cumulative distribution function (CDF) of a standard normal distribution, Φ(z). In R, the CDF of the standard normal distribution is implemented in the pnorm function. But you may want the inverse. But I could be making stuff up here

#### kjebr

##### New Member
?
Φ symbol represents the cumulative distribution function (CDF) of a standard normal distribution, Φ(z). In R, the CDF of the standard normal distribution is implemented in the pnorm function. But you may want the inverse. But I could be making stuff up here
In the article they're using R but I have no idea how to use this or where to begin.

#### Dason

?
Φ symbol represents the cumulative distribution function (CDF) of a standard normal distribution, Φ(z). In R, the CDF of the standard normal distribution is implemented in the pnorm function. But you may want the inverse. But I could be making stuff up here
No you're right. The formula requires the inverse of the cdf of the standard normal.

#### kjebr

##### New Member
No you're right. The formula requires the inverse of the cdf of the standard normal.
Would I multiply pnorm by what's in the brackets or could I input the values within the brackets to find the value of pnorm? If that makes any sense.