T Distribution

Question 1

Properties of t distribution

Answer 1

Bell curve

Symmetrical about O

Area = probability

Question 2

How do you declare t distribution

Answer 2

Let X ~ tx

x is a degrees of freedom

Degrees of freedom = sample size - 1

Question 3

When do we use t distribution

Answer 3

If x is normal with unknown variance and a small sample is taken

Question 4

How do you find the value of t distribution

Answer 4

Page 19

Tables only give left areas with - so the right side will be that but positive

Question 5

What is the formula for t confidence interval

Answer 5

-
X +/- t x sx
Square root of n

Question 6

What would you say if a claimed mean is inside the confidence interval

Answer 6

There is insufficient evidence to suggest the claim is wrong

Question 7

What would you say if a claimed mean is outside the confidence interval

Answer 7

There is significant evidence to suggest the claim is wrong

Question 8

What would you say if the 2 confidence intervals overlap

Answer 8

There is insufficient evidence to suggest the means are different

Question 9

What would you say if the 2 confidence intervals do not overlap

Answer 9

There is significant evidence to suggest the means are different

Question 10

What are the H0 and H1 of t test

Answer 10

H0 : mew = the mean
H1 : mew <
>
=\

Question 11

How do you declare the t test

Answer 11

Use a 1/2 tailed t- test at x % level using v =

Question 12

How do you find test stat of t test

Answer 12

_
X - mew
_________
sx
________
Square root of n

Question 13

How do you find the critical region of t test

Answer 13

The % level of significant and use the t table on page 19 with the level of significance n-1