Stats-Foty

Question 1

What is the central limit theorem?

Answer 1

Sampling distribution of the mean of any independent will be normal or near normal

Question 2

Where do the mean/median/mode lie in left skewed data? In right skewed?

Answer 2

Left skewed

Mean

Question 3

What are boxplots used for?

Answer 3

Display summary statistics

Question 4

What is variance?

Answer 4

Average of the square distance from each value from the mean.

S^2 = Sum (x-m)^2/(n-1)

Squared and n-1 are to maximize our variance for an unbiased assesment.

Question 5

What is the standard deviation?

Answer 5

Square root of the variance

Question 6

What is the standard error? How does it relate to sample size?

Answer 6

SEM = SD/(sqrt(N))

SEM gets smaller as sample size increases

Question 7

When to use standard deviation? When to use standard error?

Answer 7

SD = is scatter is caused by biological variability and we want to show that variability

SEM = variability is caused by experimental imprecision and we want to show precision of calculated mean

Question 8

What is formula for CI?

Answer 8

CI = X +/- (SEM * Z)

95% CI z constant = 1.96

Question 9

How do we manage outliers?

Answer 9

Grubb’s test.

Z = (mean-value)/SD

Compare this to critical values of Z.

If zcalc is less than 2tab, p>5% and must be retained