# Calculate 95% confidence interval without sample standard deviation?

I have mean 2.25 and sample size 190. I want to calculate the confidence interval (Upper Confidence level and lower confidence level) for this sample size. I know how to calculate confidence interval with standard deviation. However, I don't know standard deviation for the sample in this problem. Is there a way to find interval based on mean value for this sample?

• No, because the standard deviation could be arbitrarily large. – rubik Jul 28 '17 at 10:50
• Thank you very much @rubik for your genuine reply. Could you suggest me a technique to pick a particular range from the sample using mean having approximately same significance (or random set similar to confidence interval), please? – Mayur Mane Jul 28 '17 at 11:57
• I'm not aware of any techniques for statistical inference that could work without at least the sample standard deviation. (By the way, why cannot you calculate the sample standard deviation?) You may have more luck on Cross Validated. Also note that you haven't specified what do you want to calculate the confidence interval for. I'm assuming the mean, but remember that you can build a confidence interval for any parameter. – rubik Jul 28 '17 at 14:20