Systematic Errors

These are due to a bias in the measuring system which will produce an error (possibly the same) in every reading. If the source of the systematic error can be identified then it can be eliminated.

Here are some examples.

	When an instrument is incorrectly calibrated. Zero error is an example of this. This ammeter is not set to zero and so all readings will be out by at least what it reads now.
	When there is a change in the environment which is unaccounted for, e.g. a change in room temperature. How might this effect the stiffness of a rubber band?
	There may be an error in the system which we should account for. When you are measuring the period of a pendulum and you fail to take into account movement in the stand. What effect would this have on the readings? We always assume that ammeters have no resistance. Do they? What affect do they have on the current they are measuring?
	Parallax error is when the observed reading depends on the viewpoint of the observer. When reading the value on this measuring cylinder your eye should be at the same level.
	A resistor is assumed to be exactly 100Ω. Cheap resistors, e.g. those in schools, are rarely the value written on them.

Random errors are unpredictable and are always present.