exploratory objectives, which are less important, but still interesting. Finally, if testing a risky

intervention (such as a pharmaceutical), you should list one or more safety objectives (if this is

an efficacy study) or some efficacy objectives (if this is a safety study).

The objectives you select will determine what data you need to collect, so you have to choose

wisely to make sure all data related to those objectives can be collected in the timeframe of your

study. Also, these data will be processed from various sources, including case report forms

(CRFs), surveys, and centers providing laboratory data. These considerations may limit the

objectives you choose to study!

Drug clinical trials are usually efficacy studies. Here is an example of each type of objectives you

could have in an efficacy study:

Primary efficacy objective: To compare the effect of new hypertension (HTN) drug XYZ,

relative to old drug ABC, on changes in systolic blood pressure (SBP) from baseline to week 12,

in participants with HTN.

Secondary efficacy objective: To compare the effect of HTN drug XYZ, relative to drug ABC, on

changes in serum total cholesterol and serum triglycerides from baseline to weeks 4 and 8, in

participants with HTN.

Exploratory efficacy objective: To compare the effect of drug XYZ, relative to drug ABC, on

changes in sexual function from baseline to weeks 4, 8, and 12, in male and female subsets of

participants with HTN.

Safety objective: To evaluate the safety of drug XYZ, relative to drug ABC, in terms of the

occurrence of adverse events, changes from baseline in vital signs such as temperature and heart

rate, and changes in laboratory results of safety panels (including tests on kidney and liver

function), in participants with HTN.

For each of these objectives, it is important to specify the time range of participation subject

to the analysis (such as the first week of the trial compared to other time segments). Also, which

groups are being compared for each objective should be specified.

Hypotheses usually correspond to the objectives but are worded in a way that directly relates to the

statistical testing to be performed. So, the preceding primary objective may correspond to the

following hypothesis: “The mean 12-week reduction in SBP will be greater in the XYZ group than in

the ABC group.” Alternatively, the hypothesis may be expressed in a more formal mathematical

notation and as a null and alternate pair (see Chapters 2 and 3 for details on these terms and the

mathematical notation used):

where

of (

).