1. Which of the following is an accurate description of a P value? Select one: a

Question

1. Which of the following is an accurate description of a P value?

Select one:

a. The chance of obtaining the observed result, or one more extreme, if the null hypothesis is true

b. The probability that the null hypothesis is true

c. The range of values that with some degree of certainty include the true population parameter

d. A threshold value (commonly set at 0.05) for declaring whether a result is statistically significant

2. When should you calculate a one-tailed P value instead of a two-tailed P value?

Select one:

a. If you've collected your data but didn't plan ahead in terms of which type of P value you'd use

b. If you are sure that an observed difference could only go in one direction (e.g., group A might be the same or bigger than group B, but group B definitely won't be bigger than group A)

c. Never, you should always use a two-tailed P value

d. You should always calculate a one-tailed P value because it will be smaller and thus improve your chances of observing a statistically significant result

3. You collect gender and cholesterol data form a sample population and determine that women have a mean LDL cholesterol of 185, while men have a mean LDL cholesterol of 190. The two-tailed P value for this difference is 0.06. What can you conclude?

Select one:

a. Mean LDL cholesterol is statistically significantly higher for women than it is for men at an alpha level of 0.05

b. The 95% confidence interval for the mean difference in LDL cholesterol between men and women would not include 0

c. The 95% confidence interval for the mean difference in LDL cholesterol between men and women would include 0

d. Mean LDL cholesterol is statistically significantly higher for men than it is for women at an alpha level of 0.05

4. Which of the following P values are statistically significant at an alpha level of 0.10? Choose all that apply

Select one or more:

a. 0.09

b. 0.049

c. 0.50

d. 0.001

e. 0.051

Explanation / Answer

right choices are

(1)a. The chance of obtaining the observed result, or one more extreme, if the null hypothesis is true

The p-value is the likelihood of the observed data, given that the null hypothesis is true. The p-value is, in future experiments, the probability of obtaining results as "extreme" or more "extreme" given that the null hypothesis is true.

(2)b. If you are sure that an observed difference could only go in one direction (e.g., group A might be the same or bigger than group B, but group B definitely won't be bigger than group A)

(3) c. The 95% confidence interval for the mean difference in LDL cholesterol between men and women would include 0.

here alpha=0.05 is less than p-value=0.6, so we fail to reject H0

Zero is the null value of the parameter (in this case the difference in means). If a 95% confidence interval includes the null value, then there is no statistically meaningful or statistically significant difference between the groups.

(4) a,b,d and e,

for statistical significant p-value should be less than alpha=0.1

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