10.6 Representing variation graphically

10.6 Representing variation graphically

1. Continuous and discontinuous variation

   • Continuous
     • Quantitative, no discrete categories
     • A range of intermediate stages between 2 extreme phenotypes
       • Leaf size, worm length
     • Often polygenic
       • Affected by many genes
     • Usually affected by the environment but not usually
   • Discontinuous
     • Usually controlled by 1 or 2 genes
     • Variation within distinct categories
     • Not usually affected by environment

2. Standard deviation

   • • S = measure of spread, therefore the greater the SD the greater the spread

3. Student T-Test

   • Remember to state H0 at start of workings
   • How to calculate degrees of freedom
     • df = (n1 +n2)-2

4. Spearman's rank

   • • Rs = correlation coefficient
     • d = difference in ranks
     • E = sum of
     • n = number of pairs of data

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