FHSST Biology/Numbers

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Scientific Notation, Significant Figures,Rounding and Chi Squared Test[edit]

If you are only sure of say, both digits of a two-digit number, and put it in a formula and get a long series of numbers to the right of the decimal place, then those digits are probably not very accurate. This is the idea of significant figures.

Take 10 and divide by 3. If you are not sure that the number 10 is perfectly accurate, then you do not need to write down 3.333... and can get away with something like 3.3 or 3.33. Usually, in Biology, we only need figures to 1 decimal place, but sometimes we need them to 2 places.

The main situation in which we would need to be careful and accuate with our numbers is in statistics. In particular, we would need figures to 2 decimal places if we wanted to use the Chi (pronounced Ki) Squared Test (abbreviated as X2 test) to decide whether a result is significant or not.

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