(a) Yes, you must identify and correct errors in your sample data for using the template.
(b) If you are using sample data from previous report years, you should have identified and corrected such errors in developing your estimates then; make sure that you use the final version of your sample data.
(c) Refer to Subsection 67 for identifying and correcting errors in your sampling data during the course of an entire report year as you collect sample data.
(d) If you are using sample data from the current report year, identifying and correcting errors in the sample data now for developing sampling plans saves you from doing it when you develop your estimates later for reporting purposes.
(e) At a minimum, you should conduct the following checks to identifying potential errors:
(1) Overall consistency – UPT and PMT should be closely related across all sample units. For period-based sampling plans, check for errors if cell D26 in the PeriodCalculations worksheet is smaller than 0.5. For interval-based sampling plans, check for errors if cell D20 in the IntervalCalculations worksheet is smaller than 0.5.
(2) Consistency at the level of sampling units – UPT and PMT should both be zero or both be positive. Check for errors if one is zero but the other is positive.
(3) Comparing APTL with route length – Calculate the ratio of PMT over UPT and compare the result to the maximum length of your route. This check is not applicable to demand response services.
(4) If you consider the PPMT option, calculate the ratio of PMT over PPMT for each sample unit; the ratio should not be greater than 1.
(f) It is in your interest to keep your sample data free of errors. Experience indicates that sample data with errors tend to result in larger sample sizes than sample data free of errors.