All numeric data are *estimates* of the actual number

Observable natural variation, s_{T}^{2}, in organisms

. . - s

. . - s

. . - s

distribution of continuous traits and meristic (integer values only) traits

. . - in Genetics, classes are usually expressions of traits

. . - divide range (largest - smallest value) by number of classes = class width

. . - label midpoints (half way between bottom and top of class)

. . - display as histogram (bar graph)

. . - If one observation is in the wrong class

. . - How does the distribution change?

. . - What is the error in estimating frequency of class?

. . - Could

. . -

. . - estimates center of distribution

. . -

. . - estimates spread of distribution

. . -

. . - standard deviation = square root of variance

. . . - approx 68% of values within 1 standard deviate

. . . - approx 95% of values within 2 standard deviates

. . . - approx 99.7% of values within 3 standard deviates

Statistical tests exist to estimate probability that observed data match expected results

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© 2004 Prof. LaFrance, Ancilla College