Which of the following are suitable null hypotheses. If not,explain why.
a. Comparing two groups
Consider comparing the average blood pressure of a group ofsubjects, both before and after they are placed on a low salt diet.In this case, the null hypothesis is that a low salt diet doesreduce blood pressure, i.e., that the average blood pressure of thesubjects is the same before and after the change in diet.
b. Classification.
Assume there are two classes, labeled + and -, where we are mostinterested in the positive class, e.g., the presence of a disease.H0 is the statement that the class of an object isnegative, i.e., that the patient does not have the disease.
c. Association Analysis
For frequent patterns, the null hypothesis is that the items areindependent and thus, any pattern that we detect is spurious.
d. Clustering
The null hypothesis is that there is cluster structure in thedata beyond what might occur at random.
e. Anomaly Detection
Our assumption, H0, is that an object is notanomalous.
