Six Sigma Green Belt Certification Practice Exam

Using the student t test, how do you determine if the test is a two-tailed test?

1. a. The sign for the null hypothesis is =

2. b. The sign for the null hypothesis is <

3. c. The sign for the alternate hypothesis is =

4. d. The sign for the alternate hypothesis is <

The correct answer is: c. The sign for the alternate hypothesis is =

In hypothesis testing, the determination of whether a test is a two-tailed test depends primarily on the alternative hypothesis. A two-tailed test is used when researchers are interested in determining whether a parameter is either significantly higher or significantly lower than a certain value. This means that the alternative hypothesis posits that there is a difference, without specifying the direction of that difference. In this context, the alternate hypothesis typically includes a 'not equal to' sign (often represented as ≠), indicating that the parameter could be either greater than or less than the value specified in the null hypothesis. Since the correct choice indicates that the sign for the alternate hypothesis is equal to something, but not directly a directional hypothesis (like having a less than sign), it suggests that the alternative hypothesis would encompass the possibility of deviations in both directions from the null hypothesis’s specified value. This supports the notion of a two-tailed test, where both tails of the distribution are considered for determining significance. Thus, the selection aligns with the framework of hypothesis testing where a two-tailed test is concerned with deviations in both directions, affirming that this choice correctly identifies the nature of the test.