4. Is it accurate?

The data should be accurate. But there are a number of ways the input data could be inaccurate

Missing data

Imagine that a school wants to give an award to the student with the best attendance. All the attendance registers are loaded into the database. But from some reason, some sheets go missing. This missing data could change the result.

Deliberately wrong data

Say someone is asked to do an extremely boring job of counting cars going past a junction. They start off well, but after three hours they decide to just make up the numbers and go home instead.

Mis-reading data

A data logger has been set up to measure wind speed. But a mistake has been made in calibrating the instrument. Now all the data collected would be incorrect.