Which of the following is NOT a factor in determining relative error of closure?

The relative error of closure in surveying is a measure of the accuracy of the measurements made in a circuit or traverse. It is typically expressed as a function of the errors associated with the measurements, such as latitude and departure errors, and the length of the traverse itself.

Errors in latitude involve discrepancies in the north-south measurements, while errors in departure relate to the east-west measurements. Both these factors directly contribute to the overall error in the closure of a survey loop. Similarly, the length of the traverse affects the relative error—longer traverses can accumulate more significant errors simply due to the scale of the measurements involved.

However, the number of observation points does not directly influence the relative error of closure. While having more observation points can improve the overall reliability and accuracy of the survey by providing more data, it does not directly alter the relative error itself. Instead, it is the measurement errors (in latitude and departure) and the overall traverse length that directly affect the calculations of closure error.

Thus, identifying the number of observation points as unrelated to the computation of relative error of closure is why it stands out as the correct answer to the question.