Hi Dhirendra,

I think the first step would be to understand what these two different concepts are.

SD -

The standard deviation is a statistic that tells you how tightly all the various examples are clustered around the mean in a set of data.

More here:

https://www.robertniles.com/stats/stdev.shtml

Mean - (another name for 'Average')

The mean is the average of the numbers.

https://www.khanacademy.org/math/statistics-probability/summarizing-quantitative-data/mean-median-basics/a/mean-median-and-mode-review

The Mean indicates the average value of a data set

The SD shows the distance of each point of data from the average of a data set

Remember that in a normal distribution the mean = 0

so the SD will always be greater than the mean.

A small SD will indicate the data is less spread out

A large SD will indicate that the data is more spread out

This might also be useful:

https://www.quora.com/What-does-it-mean-when-the-standard-deviation-is-higher-than-the-mean-What-does-that-tell-you-about-the-data

I hope this helps.

Thank you so much Samantha Curle

Mean and SD are two different statistical concepts. In point of fact, mean is a measure of central tendency, while SD is a measure of variability. The mean value is one of the central figures showing the average performance profile whereas SD shows dispersion and falls between+ and - 1 and 4. As such, you need to reconsider the statistical analysis and to find what has gone awry in the process.

The other answer is that your data may not be normally distributed. For instance, if your SD is roughly equivalent to the mean your data may be exponentially distributed and you could then determine what the rate parameter may be (typically 1/mean).

Use the random number generators provided in statistical software packages to generate simulated values from a probability distribution and check if it is comparable to your data. For instance, simulate values from a normal distribution with the mean and SD you have. Do those values encompass the same range as your data? Do you expect negative values, or is the quantity of interest strictly positive?