PSY 317 Chapter 15

The manufacturer of a certain toy claims that the mean lead content in this toy is 100 ppm. A sample of 25 such toys produces xbar = 105.1 ppm. This would provide evidence against the manufacturer's claim if we can show that _________.

105.1 could rarely occur by chance if the claim were true

xbar = 105.1 ppm. evidence to prove against the null hypothesis

105.1 could rarely occur by chance if the claim were true

null hypothesis

Ho: µ = 0

The manufacturer of a certain toy claims that the mean lead content in this toy is 100 ppm. The Consumer Product Safety Commission takes a random sample of 25 such toys to evaluate the manufacturer's claim. What is the null hypothesis?

Ho: µ = 100 ppm

If we test Ho: µ = 40 vs. Ha: µ < 40, this test is

One-sided (left tail)

The data are 'statistically significant' whenever _________

P-value < α

suppose the P-value for a hypothesis test is 0.567. Alpha = 0.05, what is the appropriate conclusion?

Reject alternative hypothesis

Suppose the P-value for a hypothesis test is 0.0304. Using α = 0.05, what is the appropriate conclusion?

Reject the null hypothesis

What is the definition of the P-value applied to this problem? A consumer advocate evaluates the claim a new granola cereal contains "4 ounces of cashews in every bag. She recognizes that the amount of cashews will vary slightly from bag to bag, but suspects that the mean amount of cashews per bag is actually less than 4 ounces. Th advocate purchases a random sample of 40 bags of cereal and calculates xbar to be 3.68 ounces.

The probability, if the mean for all bag was 4 oz, of obtaining an xbar as small as 3.68

If we test Ho: µ = 40 vs. Ha: µ ≠ 40, this test is

Two-sided

Null and alternative hypotheses always refer to ________.

a population parameter

If you observe an outcome that would __________ happen if a claim were true, you would have good evidence that the claim is ___________

rarely, not true

To calculate the P-value for a significance test, we use information about the _________.

sampling distribution of xbar.

There is evidence against the null hypothesis whenever __________

the P-value is small