STATS Quiz 8.2,8.5,8.6

When performing a significance test, we're looking for convincing evidence to __________ the null hypothesis in favor of the alternative hypothesis.

• refute

• dispute

• reject

• accept

To answer the question, "Is the evidence convincing enough to reject the null?" we can't just look at our sample statistic. Why not? Because samples ________.

• are all the same

• vary

• are too small

• affect the standard deviation

A significance test produces a _______ that accounts for the variability in sampling.

• z-score

• critical value

• t*-value

• p-value

Whatever probability we choose as the cutoff for what is small is what we call the ____________________.

• importance level

• significance level

• meaningfulness level

• insightfulness level

The symbol for the significance level is ____.

• fail to reject, statistically significant

• reject, statistically significant

• fail to reject, not statistically significant

• reject, not statistically significant

Lumber companies dry freshly cut wood in kilns before selling it. A certain percentage of boards develop cracks on their ends during drying. The current drying procedure is known to produce cracks in 16% of boards. The drying supervisor wants to try a new method that she believes will result in a proportion of cracked boards that is less than 16%.

Write the appropriate hypotheses.

• Ho: p = 0.16

  Ha: p = 0.16

• Ho: p = 0.16

  Ha: p =/= 0.16

• Ho: p = 0.16

  Ha: p > 0.16

• Ho: p = 0.16

  Ha: p < 0.16

• Since our p-value of 0.027 is >undefined , we fail to reject the null hypothesis. We do not have convincing evidence that the new method is better. 

A box of Raspberry Crunch cereal contains a mean of 13 ounces with a standard deviation of 0.5 ounces.  The distribution of the contents of cereal boxes is approximately Normal.  The cereal company is afraid the boxes being over filled.  Suppose they get a random sample of 25 boxes, and find a mean of 13.2 and a standard deviation of 0.154.  Does this give evidence that the boxes are being overfilled?

• 1 sample t-test
• 2 sample t-test
• 1 proportion z-test
• chi-squared GOF test