Unit 6: TAKE NOTES!! PLEASE!!
A researcher performs two null hypothesis significance tests. One comes out at p = .04, the other at p = .06. The researcher decides that in the first case the null hypothesis should be rejected, but in the latter case, the null hypothesis is probably true. Which of the following statements about this situation is correct? Select one: a. The traditional .05 criterion is an arbitrary cutoff, so the researcher should be wary of this conclusion. b. The researcher should probably run the second experiment again, until both p values are under .05. c. The researcher is correct; a null hypothesis is false if and only if the p value is less than .05.
a. Don't trust a hoe
A researcher performs a one-sample t test, and gets t(19) = -3.1. This means that: Select one: a. the sample mean is 3.1 standard errors below the mean according to the null hypothesis. b. the sample mean is 3.1 times less likely than the mean according to the null hypothesis. c. the null hypothesis mean is equal to the sample mean plus 3.1.
a. the sample mean is 3.1 standard errors below the mean according to the null hypothesis.
Failing to reject the null hypothesis when the null hypothesis is actually false is known as a: Select one: a. Type III error b. Type II error c. Type I error d. Correct decision
b. Failing to reject the null hypothesis when the null hypothesis is actually false is a Type II error. The probability of a Type II error is 1-Power.
If a researcher finds sufficient evidence to reject a null hypothesis using an alpha-level of .05, then which of the following must be true? Select one: a. The null hypothesis must be false. b. There is sufficient evidence to reject the null hypothesis using an alpha-level of .10. c. The alternative hypothesis must be false. d. There is sufficient evidence to reject the null hypothesis using an alpha-level of .01.
b. If it is possible to reject the null using an alpha level of .05, this means that p value was less than .05. Thus, the p-value must also be less than .10. However, the p value does NOT have to be less than .01. (E.g., it could be .03.)
Under which circumstance do we reject the null hypothesis? Select one: a. If our p-value is greater than our α-level. b. If our p-value is less than our α-level. c. If our p-value is equal to our α-level.
b. The null hypothesis is rejected if the p-value is less than our α-level (which is usually 0.05)
Which of the following statements would be a typical null hypothesis? Select one: a. there is a relationship between income and height b. a defendant is guilty c. there is no difference between incomes of male and female doctors d. a given coin does not come up heads 50% of the time
c. A null hypothesis is almost always a statement that there is no effect of some experimental manipulation, or that there is no difference between two groups. Only the statement that there is no difference in income between male and female doctors is of this type.
A 95% Confidence Interval for the mean extends from -2 to 13. This means that: Select one: a. We WOULD NOT reject the null hypothesis that μ = 0, with a two-sided test and alpha = .10. b. We WOULD reject the null hypothesis that μ = 0, with a two-sided test and alpha = .10. c. We WOULD NOT reject the null hypothesis that μ = 0, with a two-sided test and alpha = .05. d. We WOULD reject the null hypothesis that μ = 0, with a two-sided test and alpha = .05.
c. A two-sided hypothesis test with alpha = .05 will reject the null if and only if the null value falls OUTSIDE the 95% confidence interval. Here the null value (0) falls INSIDE the CI, so we would not reject.
Rejecting the null hypothesis when the null hypothesis is actually true is known as a: Select one: a. Type II error b. Correct decision c. Type I error d. Type III error
c. Rejecting the null hypothesis when the null hypothesis is actually true is a Type I error. The probability of a Type I error is α, which, in psychology, is typically 0.05.
Suppose that on average, American households own 1 pet. You suspect that Massachusetts households might own more pets than the typical American household. Which of the following would be the null hypothesis? Select one: a. H0: μMass > 1 b. HA: μMass > 1 c. H0: μMass = 1 d. HA: μMass = 1
c. The null hypothesis, in this context, would be that Massachusetts households are not different from U.S. households in general, and therefore that they, too, own an average of 1 pet. The alternative hypothesis is that the mean number of pets owned by Massachusetts households is greater than 1.
A result obtained in an experiment is said to be "statistically significant" when: Select one: a. the result is consistent with our null hypothesis. b. the result has been replicated in multiple experiments. c. the probability of the result occurring by chance is less than our alpha-level. d. the result has some important real world implications.
c. To say that a result is "statistically significant" is just to say that it is unlikely to have occurred by chance, where 'unlikely' is defined as occurring with a probability less than our alpha level (usually .05).
The statistical power of an experiment is affected by which of the following: Select one: a. sample size b. how far from correct the null hypothesis actually is c. how influential the result of the experiment will be d. both a and b
d. As sample size increases, the power of an experiment to reject the null increases. As the estimated difference between the actual and null hypothesis means increases, power increases.