[mperez]

Hi,

Does anyone know what it means when the standard deviation is larger than can be explained by measurement uncertainties?

Say that the standard deviation of a slope is 0.02 cm and the uncertainty of the ruler with which it was measured is 0.01 cm. Does the uncertainty account for the standard deviation?

thanks!!

[enahs]

A standard deviation of a slope is not a well defined concept. I argue it does not exist.
You can have confidence intervals of a slope, typically reported as 95% or 98%,99%. That is, 95,98 or 99% of the time the values will fall on that curve (yes a straight line is mathematically a curve). It might sound like a standard deviation of sorts, but it is quite different.

The confidence interval of a slope is a function of the accuracy of your individual measurements, but it is very largely based on how your measurements act as a whole.

If you show data perhaps I can help more, and explain what you mean by a standard deviation of a slope.

[mperez]

It is about the slope of a Diameter vs. circumference graph using the diameter and circumference of different sizes of cylinders as the data.

[enahs]

How are you calculating a standard deviation of your slope?