Statistics
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What is the measure of central tendency?
Spread / skew of data, measures location of middle / center of distribution Mean, median, mode
What is the standard deviation? normal distribution? frequency distribution?
+/- 1 standard deviation from the mean is 68% of the data +/- 2 standard deviations from the mean is 95% of the data Normal distribution: bell curve between -2 and +2 standard deviation Frequency distribution: frequency of different outcomes / types
What is a standard deviation test?
Determines if difference is likely / unlikely to be significant Likely if difference between averages > greater standard deviation
What is a t-test?
Whether difference between data sets is significant Calculated t-value > critical value means it’s significant
What is the p-value in biology?
p = 0.05 (5%) 5% probability differences are due to chance rather than real difference
How are degrees of freedom calculated for t-tests?
df = (total of first data set, n’a + total of second data set, n’b) - 2
What goes into a standard deviation conclusion?
Averages for each condition Difference in averages, compare to standard deviations Interpret if indicates likely significant difference Report analysis in terms of focused question
What goes into a t-test conclusion?
Averages for each condition Report calculated value of t, critical value of t, degrees of freedom, p-value Interpret if indicates significant difference Report analysis in terms of focused question
What is a chi-squared test?
Used to determine if hypothesis should be accepted / rejected Erroneous decision > 5% of the time Degrees of freedom is 1 less than number of phenotypes Calculated value < table value to accept