Statistics in Biology

Question 1

Mean (x bar)

Answer 1

• Measurement of the max height of the curve
• Average value - comparing one sample with another
• Add all the values and divide by the number of values

Question 2

Standard deviation

Answer 2

• Measure of the width of the curve
• Range of values either side of the mean

X - entire list of numbers
x bar - arithmetic mean of all the numbers in the list
n - how many numbers there are in the list
E - sum - add together

Small SD - little variety in data - values are close to mean = more significant
Large SD - lot of variety

Question 3

Standard error

Answer 3

• Look for differences between the mean values of measurements from the sample and population that the sample was taken

SE = SD/ square root n(sample size)

Question 4

Statistical test

Answer 4

• Answers in term of probability that our measured differences occurred due to chance

Question 5

Chi squared

Answer 5

• Looking for the number of individuals in a particular category
• Compares the observed results to those that you would expect if they were due to chance
• Null hypothesis - assume that any difference between observed results + expected results is due to chance
• Disprove the null hypothesis = no difference
• Significant = probability is due to chance is less than 5%

Question 6

Spearman Rank Correlation

Answer 6

• Taking measurements

- Looks for associations between different measurements from the same sample