What is the null hypothesis?

Question

1. The Coca-Cola company wants to evaluate how consumers will respond to a newly developed energy drink. The key question is whether consumer’s preference for the drink depends on the amount of caffeine. Twelve customers were asked to participate in the study. Half of the consumers rate a drink that has 50 mg/12 oz.; half of the consumers rate a drink that has 100 mg/12 oz. Their ratings, on a scale from 1 = dislike a lot to 7 = like a lot, are shown below. Conduct an appropriate statistical test to determine if consumers differ in their preference for the drink based on amount of caffeine. Use alpha = .01. 50 mg/12 oz.: 5 6 4 5 6 4 100 mg/12 oz.: 5 3 5 3 4 4

Answer 1

Thus, to add to what Edward said:

 

H₀: u₁=u₂

Answer 2

The null hypotheses is generally a statement that there is no effect, no difference, or no change from historical values. This question asks to "determine if consumers differ in their preference".  So the null hypotheses would be that there is no difference in preference for the drink based on the amount of caffeine.