Answer:
d) a correct failure to reject the null hypothesis
Step-by-step explanation:
A hypothesis test can be write as follows:
[tex]H_0 =[/tex] The treatment wasn't effective
[tex]H_1 =[/tex] The treatment was effective
Where [tex]H_0[/tex] is the null hypothesis and [tex]H_1[/tex] is the alternative hypothesis.
In a hypothesis test we usually observe the behavior of a certain characteristic that can quantify and summarise the data in some way, we could look at the mean, median, standard deviation, quantiles and much more. Let's say for instance that we've choosen to analyse the mean of the observations, and we conclude that the mean between the treatment and a placebo were very close to each other, so statistically they are the same. In other words the treatment have the same value as the placebo treatment.
If we can conclude if there is a significant difference between the treatments than we can say for sure that they are different, and in statistics we want to minimize the errors as much as possible, that's why we introduce the uncertainty in our estimatives. When we can say that the treatment is effective, with a degree of uncertainty, than we fail to reject the null hypothesis.