More on hypothesis testing

True false questions about hypothesis testing.
The basic facts about hypothesis testing.


Practice problems

In testing for psychic powers, researchers use a deck with five different shapes, as shown in the picture on the left. If the deck is re-shuffled every time, the probability of guessing correctly by pure chance is 1/5 or p = .2 written in decimal. The test would be one tailed high, and we use the z-score table, so the threshold for 95% confidence is = 1.645 and the threshold for 99% confidence is z = 2.325.

Questions:

1. If a subject gets 3 out of 10 correct in a psychic test, are we 95% confident the subject shows psychic powers?

2. If a subject gets 4 out of 10 correct in a psychic test, are we 95% confident the subject shows psychic powers? Are we 99% confident?

3. If a subject gets 5 out of 10 correct in a psychic test, are we 95% confident the subject shows psychic powers? Are we 99% confident?

4. If a subject gets 30 out of 100 correct in a psychic test, are we 95% confident the subject shows psychic powers? Are we 99% confident?

5. If n = 100 and p = .2 in a high one tailed test, find the minimum number of correct answers for rejecting H0 to the 95% confidence level and the 90% confidence level.

Answers in the first comment.

Bonus questions

We have a sample with n = 40, x-bar = 172.5 and sx = 119.5.

1. What is the one tailed low threshold for 95% confidence?

2. What is the one tailed high threshold for 99% confidence?

3. If H0 is mux = 200, are we 95% confident we can reject this for HA: mux < 200?

4. If H0 is mux = 100, are we 99% confident we can reject this for HA: mux > 100?

Answers in second comment.

Practice problems for confidence of victory and confidence intervals

Links to earlier posts about confidence of victory.

Data from recent polls.

Boxer vs. Fiorina U.S. Senate (CA)
Date: 10/2
Boxer: 49%
Fiorina: 44%
n = 448

Brown vs. Whitman Governor (CA)
Brown: 50%
Whitman: 43%
n = 448

For both of these polls:
1) Find the 95% confidence interval for both candidates
2) Since the two top candidate poll over 90% total, do the confidence of victory, rounding to the nearest 5% if the value is under 90% and to the nearest 1% if the value of over 90%.

Answers in the comments.