How do I calculate the standard deviation of the calibration line?

Question

Based on this table:

I have obtained the standard deviation at each concentration, how can I calculate the standard deviation of the calibration line (not at each concentration)?

Answer 1

In standard linear regression (the calibration line), one of the underlying assumptions is that the standard deviation is constant. This "true" or "population" standard deviation $\sigma$ is usually estimated by something called Mean Squared Error (MSE).

$MSE = \frac{\sum_{i=1}^n(y_i-\hat{y})^2}{n-2}$

Where $\hat{y_i} = 1965.8x_i + 2228.3$ (from your excel plot).

I would argue that this is the best estimate for the population standard deviation for any concentration.