In order for information to be useful it needs to be complete. If parts of the information is missing then you will not be able to make use of it or make accurate decisions.
Remember those exam papers that you were doing for revision during your study leave. Your teacher wanted you to work your way through them and check your answers against the model answers.
What if you were only given the second half of the model answer and the first half was missing? How useful would it be to you?
You still want to plan the family picnic for tomorrow.
However when you check the weather forecast you are only told what the weather in the morning will be like. There is nothing about the afternoon.
You can't really make a decision just based upon what the morning weather is likely to be.
Remember when you were feeling ill and you needed to make an appointment to see your doctor.
How useful would it be if the receptionist just told you that you could have an appointment at 14.25?
Does she mean today, tomorrow or next week?
challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: Completeness of Information