what do you mean by two standard deviation?

Question

I understand standard deviation a bit but not fully so kindly someone explain two standard deviation.

In: 5

Answer 1

There’s a way to model how data is distributed called a normal distribution or Gaussian distribution. The x axis is the value and the y axis is how likely that is. There’s a peak at the mean value (ie the mean is the most likely) and the likelihood decreases as you get further away (how quickly depends on the standard deviation). You can use this to determine how likely a value is. 68% of data points fall within +- one standard deviation of the mean. 95% of the points fall within +- 2 standard deviations. So when someone uses two standard deviations, they mean 95% chance of the data falling within 2 standard deviations of the mean.