Exam 13: The Comparison of Two Conditions

A professor wants to compare the test scores of his two psychology classes (Class A and Class B). Each class has 20 students. The professor calculates a t value of 2.3 and concludes that Class B has a mean test score that is significantly higher than Class A. What is the effect size associated with this statistical test?

Rather than personally reading the research instructions to each subject, an investigator has the subjects listen to a tape recording of the research instructions. In this case, the researcher is trying to optimize t by

Ed wants to know if students did significantly better on a test the second time they took it. Which test of statistical significance should Ed use?

Which of the following conditions will result in larger t values?

A waitress is interested in whether she receives larger tips in general from her male customers than her female customers. She records the gender of the customer who paid the bill and the amount of the tip over a two-day period. Statistically speaking, the "signal" in this research scenario would be

Significance tests have two components. They are:

In which of the following situations would one use an independent t test?

In a test of the impact of delay on recall, a researcher has two groups study a list of words. For the immediate recall condition, the researcher has the subjects recall the words immediately after the study period has ended. For the delay recall condition, the researcher has the subjects recall the words three minutes after the study period has ended. The researcher found that there was not a significant difference in the number of words recalled between the two conditions. The researcher decides to conduct the study again, this time using fifteen minutes as the delay between studying and recalling the list. The researcher is trying to optimize t by

Harry is using an independent t test to compare the means of two groups. There are ten participants in each group. How many degrees of freedom would be associated with this statistical test?

Uriel wants to know if the men in his class spend more time watching sports on television than the women. Uriel asks 13 women in his class to keep track of the number of hours they spent watching sports on television during a seven-day period. He asks 12 men in his class to do the same. What would be the degrees of freedom associated with the t test in this situation?

With 8 degrees of freedom, Linda finds that the probability associated with her obtained t value of 1.9 is p =.047 (one-tailed). What should Linda conclude?

The t distribution gradually approximates _______________ as the sample size increases.

The p value associated with a statistical test indicates __________ while the associated effect size indicates __________.

What is meant by a "signal-to-noise ratio"? Why does this characterize statistical significance testing using the t test?

In a signal-to-noise ratio, the "noise" represents the

Which of the following measures represents the "noise" component in the t test?

What does the p value associated with an obtained t value indicate?

Explain the conceptual relationship: Significance test = Size of effect × Size of study.

Brian wants to compare the test scores in one class to the test scores in another class. Which test of statistical significance should Brian use?

Describe the three ways that one can strengthen or maximize t.