Statistical Methods- Lectures 8/9

Question 1

What are sample statistics?

Answer 1

Sample mean (x̄) and sample standard deviation (SD, s) describe the sample from which they were calculated

Question 2

What are population parameters?

Answer 2

Population mean (μ) and population SD (σ) describe the entire population, but we usually don’t know their values since we can’t observe the whole population

Question 3

What is sample to populations?

Answer 3

Sample mean (x̄) and sample SD (s) are obtained from a sample, but are used to estimate the mean and SD of the population

Question 4

What is sample to sample?

Answer 4

Sampling variability refers to sample means varying from (imaginary) sample to sample and the standard deviation of the sample means is called the standard error of the sample mean.
The distribution of these sample means is the sampling distribution

Question 5

How do you calculate the standard error?

Answer 5

σ x̄=s/n^1/2

Question 6

What is the distribution of the sample mean approximated by?

Answer 6

Under certain conditions (CLT), the distribution of the sample mean is well approximated by a normal model:
x̄~ N(mean=μ, SE=σ/n^1/2)

Question 7

What is the confidence interval?

Answer 7

The confidence interval is a range of plausible values, calculated from the data, to estimate an unknown parameter

Question 8

What is a hypothesis test?

Answer 8

The hypothesis test is a decision rule, in the light of the data, on the perceived truth of otherwise of a proposition or hypothesis