Data Quality Control

Cooperators when reading the maximum and minimum thermometers sometimes record the minimum temperature in the maximum temperature column. This error is determined by NCDC through their quality control (QC) program that corrects the error in the data base. Because the data is key punched in, errors can occur even though the data is double punched which means that it is punched into the system twice and the two entries compared. These error along with errors where the cooperator writes a large number instead of the correct number are determined again using the QC program that look for numbers out of range of reasonable numbers  and compares the numbers to adjacent station values and then flags these numbers to be looked at by a person. Rain gage errors can exist when the cooperator reads the rain gage stick on the side recording mm instead of inches. This is determined by the QC program when rain fall values suddenly become larger than normal.