A recent psychiatric study by Baethge et al (2005) examined hallucinations in bipolar disorder vs schizophrenic patients. The sample ratio of 1:2 (bipolar vs schizophrenic) was set by the investigators, yielding 65 hallucinating bipolar disorder patients and 130 hallucinating schizophrenic patients. One variable that they compared these patient groups on was the presence of auditory hallucinations. The data are summarized in the table below.

Determine whether these patient groups differed with respect to auditory hallucinations. For this, first state the appropriate null hypothesis and then test this null hypothesis.

Auditory Hallucinations	Patient group Bipolar Schizophrenia
Absent	28	33
Present	37	97