The effect of atmospheric pressure on EDM measurement is an example of a:

The effect of atmospheric pressure on Electronic Distance Measurement (EDM) is classified as a systematic error because it consistently affects measurements in a predictable manner. Systematic errors stem from identifiable causes that lead to deviations in the data from the true value, resulting in measurements that are consistently too high or too low.

In the case of EDM, the speed of light used in the calculations for distance measurement can vary with changes in atmospheric pressure, temperature, and humidity. Since these environmental factors can be predicted and compensated for using models or corrections, the resulting error is systematic rather than random. This is distinct from random errors, which arise from unpredictable fluctuations in measurements due to various factors, leading to results that scatter around the true value without a clear pattern.

Blunders, on the other hand, are caused by mistakes in data collection or recording and would not typically be associated with natural atmospheric conditions. Similarly, one sigma errors refer to statistical variations that occur within a normal distribution, and are not specifically linked to the ongoing influence of atmospheric pressure.

Thus, understanding that atmospheric conditions introduce systematic influences in EDM measurements helps surveyors apply appropriate corrections to ensure accuracy in their distance measurements.