Question

Automobile manufacturers are interested in the difference in reaction times for drivers reacting to traditional incandescent lights and to LED lights. A sample of 19 drivers are told to press a button as soon as they see a light flash in front of them and the reaction time was measured in milliseconds. Each driver was shown each type of light. A 90% confidence interval for the average difference between the two reaction times (traditional - LED) was (-306.28, -50.17). Which of the following is the appropriate conclusion?

1. We are 90% confident that the average difference in reaction times for all drivers is negative, with the higher reaction time being with traditional lighting.

2. We are 90% confident that the average difference in reaction times for all drivers is positive, with the higher reaction time being with traditional lighting.

3. We are 90% confident that the average difference in reaction times for all drivers is negative, with the higher reaction time being with LED lighting.

4. We are 90% confident that the average difference in reaction times for all drivers is positive, with the higher reaction time being with LED lighting.

5. There is not a significant difference in the average reaction times for the two different types of lighting.

Please explain how you got the answer.

Answer 1

Solution:

Correct Answer:

3. We are 90% confident that the average difference in reaction times for all drivers is negative, with the higher reaction time being with LED lighting.

Explanation:

For the given 90% confidence interval for average difference in reaction times, both upper and lower limits are negative in nature. The negative difference indicates that LED lighting have higher reaction time because we consider the difference as traditional minus LED.