T-tests and comparing averages

Question 1

What is the z-test?

Answer 1

used for comparing 2 samples (or means) for large sample sizes (over 30)

Question 2

What is the formula for z-tests? (dont need to remember)

Answer 2

(X1-X2)/ Square root ((SD1/n1) + (SD2/n2))

Question 3

What average comparing test is used for samples below 30 samples?

Answer 3

t-test which takes into account uncertainty

Question 4

What does a larger z- / t score mean?

Answer 4

shows that the difference between sample means is greater than the pooled standard error, indicating a more significant difference between the samples

Question 5

What can the z-/ t score be compared to?

Answer 5

critical value which indicates if
the differences between the samples are significant when fall in certain confidence level

Question 6

What is a confidence interval?

Answer 6

the range of values which contains the true mean of the population with a certain
probability.

Question 7

What does an overlap between confidence intervals mean?

Answer 7

two samples are likely to be the same (or very similar). Difference may just be due to sampling error.

Question 8

What is the p-value?

Answer 8

indicates whether the observed difference between samples falls within or outside of the confidence interval

Question 9

What does a lower p-value mean?

Answer 9

greater statistical significance of observed difference