Hi,

Can you clarify exactly what you expect to see. The SD you've calculated of ,0018 is indeed correct. You can check it from first principles by squaring all the differences between the Mean (0.5) and the column L values, then taking the square root of the sum of all those deviations from the mean.

If you change the chart type to the first of the xy scatter charts (without lines or markers) I think you'll see the curve you're looking for.