Question 1

The termerror is used in two different ways in hypothesis testing:

1. Type I error (or Type II), and
2. Standard error.

Explain each type of error. What is the probability of a Type I error? What can a researcher do to influence the probability of a Type I error? What is the probability of a Type II error?

Question 2

A local university requires that all first-year students complete a math course during the first semester. This year the university is evaluating a new online version of the course. A random sample ofn = 20 students is selected and the students are placed in the online course. At the end of the semester, all students take the same math exam. The average score for the sample ofn = 20 students is M = 85. For the general population of students who took the traditional lecture class, scores on the exam are normally distributed with a = 75 and = 15.

Can we conclude that scores on the math exam for the sample of students who took the new online course are significantly different from those of the general population of students (who took the traditional lecture course)? Use a two-tailed test with = .05. Be sure to state your null hypothesis, a decision about that null hypothesis, and a conclusion explaining your results with an APA format statement. Calculate Cohen's d if necessary.

Question 3

A researcher would like to determine whether an over-the-counter herbal nasal spray has an effect on mental alertness for infants. A sample ofn = 18 infants is obtained, and each baby is given a standard dose of the spray one hour before being tested for mental alertness. For the general population of infants, scores on a mental alertness screening test are normally distributed with = 60. The infants in the sample had an average score of M = 54 and an S = 8.

Can the researcher conclude that scores on the screening test are significantly different after administering the spray? Use a two-tailed test with = .05. Be sure to state your null hypothesis, a decision about that null hypothesis, and a conclusion explaining your results with an APA format statement. Calculate Cohen's d if necessary.