Question

what is the difference between systematic error and random error.please explain. thanks

Answer 1

The latest astronomy cast podcast covered this exact subject

but a systematic error tends to move the mean by altering the test results in a predictable manner. Because of experiment design or measurement the results are off. So for instance if you were making measurements with a broken ruler.

Random error has to do with making enough tests to statistically eliminate the chance that your measurement is just noise.

Answer 2

In a nutshell, a systematic error is a problem that you can't overcome because it's a problem with the experiment itself. For instance, if you're measuring a colour change in a chemistry reaction and you have to rely on your eyes, there's a systematic error there because your eyes are not as reliable as a machine. The error is part of the system...part of the equipment. Or say you have a pair of scales you're using to weigh something, and the scales aren't that reliable? Say they always under-measure by a few grams. That's a systematic error because it's part of your experiment and not something you can change. You just have to live with it.

A random error is something that you can't predict in advance. For instance with the example I just gave, if you know your scales are a bit faulty, you can predict that and account for it. You an adjust your results. A random error is something that "goes wrong" in the experiment itslef for instance, someone might breathe on the reaction and blow some of the powder away by a tiny bit. Or, the temperature in the room might suddenly drop because a cloud goes over the sun and lowers the room temp by half a degree or something? Maybe if you're measuring heart rate, the person suddenly has a mild panic attack...it's an error that won't occur every time.

So in summary Systematic error: part of the experiment, predictable, occurs each time you measure.

Random error: external source causes problems, no way of predicting, will only occur sometimes.

Answer 3

Systematic error are errors :
a) due to the condition of measuring instrument
b) state of environment in which measurement are taken
Eg : calibration error or zero error
Random error :
a) Mistake made by observer
Eg : Parallax error