# Resolved: population standard deviation

hey!

for calculating standard error we need population standard deviation and if we know population standard deviation then why dont we find mean of population directly rather then using confidence intervals to estimate population mean ?

thanks

Hi Uzair!

Thanks for reaching out!

Please note that knowing the population standard deviation doesn't mean that we know the population mean. Calculating the population mean directly requires having the entire population data, which is often too difficult or even impossible to obtain. In most cases, we only have a sample from the population. Therefore, we use the sample mean to estimate the population mean and we calculate a confidence interval to obtain the uncertainty of this estimation.

Hope this helps.

Best,

Ivan

hey Ivan

appreciate ur detailed response but my point is that if we have population standard deviation then it implies that we have data for population , otherwise how did we calculate population standard deviation in first place .

thanks

Hi Uzair!

You raised a valid point.

However, when we refer to the population standard deviation in estimating the population mean, it doesn't necessarily mean we have the actual population data. The population standard deviation is often a known value from previous studies or established benchmarks.

Best,

Ivan