I used to think that random and systematic errors were the same, until today. Random error is caused by any factors like unknown and unpredictable changes in the experiment that randomly affect measurement of the variable across the sample, which affects the precision of the result. An example of this could be each person’s mood that can inflate or deflate their performance on any occasion. It is also the result of either the carelessness of the experimenter to take the same measurement in exactly the same way to get exact the same number.

Systematic Errors on the other hand, is opposite to random errors. They usually come from the experiments and not from the experimenter. It differs from the true value by a fixed amount. For example, a cloth tape measure that you use to measure the length of an object had been stretched out from years of use. As a result, all of your length measurements were too small. They result is always constantly wrong because all of the data is off in the same direction: either to high or too low.

In one of our measurements we used the triple beam balance to measure a rock. I think there was a random error when we made that experiment, not because there was something wrong with the balance, but maybe because we interpreted the result wrongly or because of the wind, making the weight heavier. It produced different results. Another measurement in which I think would be a random error is using the metric stick when we measured the height of the table. The edge of the table is very broad, thus making it very hard to find the exact measure.

To avoid making errors in the future, I would pilot test the instruments, getting feedback from respondents regarding how easy or hard the measure was and information about how the testing environment affected their performance. By taking more data, random errors can be reduced by averaging over a large number of observations. Though systematic errors are hard to overcome, one thing I could do is to make sure that the gadget that I would use is not defective or broken.


~ by Kenners on July 3, 2010.

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