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Vulnerable population is one of the important parts of our population which also need to be benefited from the results of clinical research. In view of their limited autonomy it may not be easy to conduct clinical research such as clinical trials in them because of ethical issues. When it is must to conduct clinical trial in this population, along with ethical considerations, some statistical and clinical research issues may also be addressed to give the objectivity to the decision of conducting trials in this population, which is not in a position to convey their acceptance of participating in the trial independently. The paper discusses the issues in vulnerable population through the concepts in clinical research and some objective ethical considerations before arriving at the decision of conducting a clinical trial.

Establishing the appropriate hypothesis is one of the important steps for carrying out the statistical tests/analysis. Its understanding is important for interpreting the results of statistical analysis. The current communication attempts to provide the concept of testing of hypothesis in non inferiority and equivalence trials, where the null hypothesis is just reverse of what is set up for conventional superiority trials. It is similarly looked for rejection for establishing the fact the researcher is intending to prove. It is important to mention that equivalence or non inferiority cannot be proved by accepting the null hypothesis of no difference. Hence, establishing the appropriate statistical hypothesis is extremely important to arrive at meaningful conclusion for the set objectives in research.

Introduction: Cancer is one of the leading causes of mortality in Indian population with control approach of varied kind which the health system of the country needs to prioritize. The tobacco related cancer which account for major share of all the cancers could be largely controlled through primary prevention a strategy effective in terms of resources hence take priority in terms of cancer control activities. It would be worthwhile to study the cancer of sites and relative magnitude of the cancers which are tobacco related and are amenable for prevention. Materials and Methods: The age specific cancer incidence rates of cancer as available from the consolidated reports of the National Cancer Registry Program of Indian Council of Medical Research for the years 1990-96 an 2001-04 were utilized for computing proportion of tobacco related cancers which included population based cancer registries at Bangalore, Bhopal, Barshi a rural registry in Maharashtra, Chennai, Delhi and Mumbai. As defined cancer of the sites oral cavity, lip, tongue, oropharynx, hypopharnx, pharynx, oesophagus, larynx, lung, urinary bladder were considered as tobacco related cancers. The statistical evaluation of proportion of tobacco related cancers between two time periods under consideration was carried out by proportion test. Results: There was a significant decline of proportion of tobacco related cancers from 1990-96 to 2003 for all the registries except Bhopal where around 50% of the total cancers attributed to tobacco habits for the two time periods under consideration. The Barshi also reported a decline but was not statistically significant. In females the proportion of tobacco related cancers ranged between 17% in Bangalore 10% in Delhi for the two time periods under review. All the registries showed significant decline in proportion of tobacco related cancers for the periods under consideration, except Delhi and Bhopal, while rural registry at Barshi revealed an increase of 3.3 %. The gender difference of the proportion of tobacco related cancers ranges between 19.8% to 34% during the period 1990-96, while it was 18.5% to 35% for the period 2001-03. While examining the difference between gender gap between the two time periods, the results from Mumbai registry revealed significant decline.