Standard deviation

[kjebr]

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]

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]

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]

perhaps feed bracket data into norminv distribution? But if you provided content info that would help.

 

[hlsmith]

?
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]

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.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4383202/
it's equation 9

 

[kjebr]

?
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]

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.

 

[Dason]

You would input what's in the parenthesis into the function. But pnorm is the cdf of the normal and we want the inverse of that. It sounds like you're using R so use qnorm instead.

 

[kjebr]

You would input what's in the parenthesis into the function. But pnorm is the cdf of the normal and we want the inverse of that. It sounds like you're using R so use qnorm instead.

Okay so just to clarify I enter the values I get within the brackets into qnorm and multiply by 2 I'll get the denominator?