z-test (S.P.2.3)

z-test (S.P.2.3)

NC.M4.SP.2.3 Implement a one proportion z-test to determine if an observed proportion is significantly different from a hypothesized proportion

S.P.2.3

NC.M4.SP.2.3 Implement a one proportion z-test to determine if an observed proportion is significantly different from a hypothesized proportion

Can only use when the 10% condition and the Normal Large counts Condition are both met

Multiple Choice

Identify the mean of the sampling distribution

• 0.75

• 0.25

Multiple Choice

Does it pass the 10% condition?

hint: is 1000 young adults less than 10% of all young adults?

• Yes

• NO

Multiple Choice

Calculate the standard deviation of the sampling distribution

• 0.029

• 0.014

Meaning

This means that the proportion of young adults who watch online videos in a sample of 1000 typically vary by 0.014 from the true proportion of 0.75 (like the margin of error)

Multiple Choice

Does it pass the normal large count condition?

hint: is 0.75 x 1000 and 0.25 x 1000 greater than 10?

• yes

• no

Using a Z-test

Both conditions are met, so now we can use the z-test. We will take the standard deviation that we already have to help solve.

Open Ended

Part 1: Use the picture to help you find the first z-score. Think about where these numbers came from

Open Ended

Part 2: Use the picture to help you find the second z-score. Think about where these numbers came from.

P-Values

p-values of a test are the probability of getting evidence for the alternative hypothesis

We can get the p-values by looking at table A.

Here are our z-scores

Open Ended

The p-value for a z-score of -1.43 is 0.0764 and the p-value for a z-score of 1.43 is 0.9222. Make a guess as to how we would use these to numbers to find the probability that a random sample of a 1000 young adults will result within 2 percentage points of the true value.

Open Ended

The answer is 0.8458. What do we do with 0.9222 and 0.0764 to obtain this answer?

Poll

How are you feeling so far on z-test?

• not good

• somewhat good

• good

• I love it

Open Ended

Please write any specific questions you have here. On Thursday we will be using z-test to test a hypothesis.