Question

Help please

Answer 1

When computing a t-test, it is important to distinguish between directional and nondirectional hypotheses as the direction will determine the rejection regions. Describe how the rejection regions would differ according to the type of hypothesis you would use.


An insurance company asks you to determine whether older drivers are safer than younger ones. Provide a directional hypothesis related to this study. Then, explain how you would need to change the hypothesis so that it would be nondirectional. What happens to the rejection regions and why? Which of the two hypotheses do you think is more appropriate and why?

Answer 2

\[H_{O}: p = R\]
Directional:
\[H_{A}≥R\] or \[H_{A}≤R\]
Nondirectional:
\[H_{A}≠R\]
Directional hypotheses have alternate hypotheses that point in some direction as to having a value less than or greater than the quantity denoted by the null hypothesis. Nondirectional hypotheses simply state that the alternate hypothesized value is different than the null hypothesized value.

In your example...

\[H_{O}: p = ∂_{older} - ∂_{younger} = 0\]
\[H_{A}: p ≤ 0\]where "∂" represents the total accident occurrence rate in set age groups (older = 31+; younger = 16-30) in the past year.

This is unidirectional because it hypothesizes that the trend of accident occurrences/driving safety rates in variant age groups tends toward one direction.

To make the hypothesis nondirectional, simply reword the hypothesis such that it doesn't indicate the general trend of accident occurrences/driving safety rates tending towards one direction. EXAMPLE: An insurance company asks you to determine whether a difference exists in the accident rates between younger and older drivers.

This should be more than enough information to answer the remaining few questions with.

Answer 3

thanks so much