1 samp tests (ch 9 and 10)

Question 1

What does a “significance level of .02” mean?

Answer 1

set alpha= .02 and reject only below that

Question 2

What does statistically significant mean?

Answer 2

When you’re p value is below alpha, it is statistically significant. It was SO WEIRD, we rejected our initial hypothesis.

Question 3

Can you accept a null hypothesis? Can you say “keep the null?”

Answer 3

Never accept a Ho, don’t keep the Null. simply “FAIL TO REJECT THE NULL”

Question 4

Do you use p-hat or p-null when you check the success/failure condition?

Answer 4

use p null

Question 5

How do you write conclusion if you reject?

Answer 5

With such a low p-value, I reject the null hypothesis. There is strong evidence that {the proportion of candles that smell like cheeseburgers) has changed.

Question 6

If you are doing a 2 tailed test with alpha=.05.. What confidence interval goes with that?

Answer 6

95% confidence interval (there is .025 in each tail)

Question 7

How do you write conclusion if you fail to reject?

Answer 7

With a p-value this high. I fail to reject the null. There is not enough evidence to say that (more students like eggnog now).

Question 8

What is a p-value?

Answer 8

It is the probability of getting your sample statistic randomly if the null were true. Basically, how likely is it that your sample statistic came from the Null Model.

Question 9

One tail or 2 tailed? How do you tell?

Answer 9

if it just says “changed” or “different”.. Then it is 2 sided.. DOUBLE THE P VALUE at ent! If it says “more” “less than” “greater” etc.. Then it is just one sided..

Question 10

Can you prove a null hypothesis true?

Answer 10

NO.. We just fail to reject it

Question 11

Do you use p-hat or p-null when you calculate your standard deviation of null model?

Answer 11

use p-null..

Question 12

Why would conclusions drawn from confidence intervals differ from those drawn from hypothesis tests?

Answer 12

Could be a one tail 2 tail mix up OR?. Think about how the SE is calculated. With confidence intervals, we use information from the sample (sd of sample or p-hat from sample), with hypothesis tests we use infromation from assumed parameters, the NULL (null s.d. or null p)

Question 13

What are the 3 steps in hypothesis testing AFTER YOU CHECK CONDITIONS?

Answer 13

1. Make your Ho and Ha 2. Make a Null Model (centered at null, use your Ho as center and in calculations, use your sample size).. This is a sampling distribution for the statistics if the null were true. 3. THINK then CHECK. use your statistic (p-hat, x-bar, phat1-phat2, xbar1-xbar2) to calculate your test statistic and then p value

Question 14

What does PHANTOMSA stand for?

Answer 14

Parameter, Hypothesis, Assumptions, Name the test, Test Statistic, Obtain P VALUE, Make Decision, State conclusion in context, ANSWER QUESTION

Question 15

what is a test statistic?

Answer 15

a t or z score (or chi squared) that you use to find a p value. It is how many s.d. away your statistic is away from the null parameter.

Question 16

What is a null model?

Answer 16

It is a sampling distribution. It tells us how sample statistics would vary if the null were true. It is centered at the null.

Question 17

If you are doing a 1 tailed test with alpha=.05.. What confidence interval goes with that?

Answer 17

90% confidence interval (there is .05 in ONE tail)

Question 18

What are the xbar and mu in t-test on TI?

Answer 18

xbar is your sample mean, mu is your hypothesized population mean

Question 19

When do you use 1 prop z test instead of one prop t test?

Answer 19

There is no 1 prop t test. You use Z for props. T for means.

Question 20

Why is randomization a condition?

Answer 20

Because we understand randomness. We study it. We call it probability.