standard deviation Flashcards
standard deviation equation
sd= square root Σ (x-mean)squared / n-1
x= observation
Σ = sum off
n= sample size
The ear lengths of a population of rabbits was measured.Ear lengths (mm): 62, 60, 59, 61, 60, 58, 59, 60, 57, 56, 59, 58, 60, 59, 57Calculate the mean and standard deviation.
Step 1: Calculate the mean
Mean = 885 ÷ 15 = 59 mm
Step 2: Find the difference between each value and the mean
Subtract the mean from each value to find the difference
Example: 62 - 59 = 3
Step 3: Square each difference
Square the difference for each value
Example: 32 = 9
Step 4: Total the differences
Step 5: Divide the total by (n-1) to get value A
36 ÷ (15 - 1) = 36 ÷ 14 = 2.571
Step 6: Get the square root of value A