Can someone please explain standard deviation and what we actually need to know?
I know it’s something like the lower the standard deviation, the more consistent (reliable) the data is.
How does it then also relate to validity?
Standard deviation is related to the bell curve. 1 standard deviation either side of the mean always includes 68% of results, so lower standard deviation means more tightly grouped results/ narrower bell curve.
Therfore, lower standard deviation increases reliability.
The standard deviation does not provide information about validity.
Note: standard deviation is a descriptive statistic in the study design. P-value is an inferential statistic not in the study design