The National Sample Survey demonstrated that tuberculosis is one of India's major public health problems, disease being equally prevalent in both rural and urban areas. To bring about the reduction of the tuberculosis problem in a limited time the programmes developed at National Tuberculosis Institute (NTI) must have the following characteristics: i) they must be firmly rooted in the general health services and contribute to their development. ii) they must be applicable to the large majority of the districts of India. The existing clinical knowledge of tuberculosis should be brought to the realm of public health application, for which NTI must accumulate a body of knowledge on the efficiency of various control programmes under field conditions and their operational feasibility.

Operations Research at NTI consists of following elements (i) Data collection on (a) epidemiological factors by conducting base line and longitudinal surveys (b) operational factors by comparing Mass Campaign approaches and Community Development Approaches (c) Sociological and economic factors by studying the awareness of symptoms among TB patients, economic consequences of TB and acceptability of long term drug treatment (ii) construction of various epidemetric and operational models to give information on the efficacy of various tuberculosis programmes (iii) test run at the moment NTI is operating a District TB Programme (DTP) in Anantapur and a city programme in Bangalore. These programmes have been formulated to a large extent on the basis of preliminary data not organised in model form. Some provisional conclusions are beginning to emerge from the various elements of the Operations Research Programme operating for a year. The general health services are proving to be capable of playing their essential role in the diagnosis and treatment of tuberculosis, provided they are assisted, at district level, by a special tuberculosis service for planning, partial supervision, evaluation and referral. With existing chemotherapy the treatment organisation is the most crucial part of the tuberculosis services, and the decisive role is played by the field organization engaged in preventing and curing treatment default. The most critical requirement of any control programme is an ample provision of drugs, to be supplied free of cost to the patients. Over half the X-ray active cases (including more than three quarters of the sputum positive cases) are aware of symptoms of the disease, and Case-finding can therefore, for some time to come, be based on the self advertising attraction of a free treatment service within a walking distance, associated with a simple sputum diagnosis at Primary Health Centre level and referral X-ray diagnosis at taluk or district level. NTI's task is formidable, its resources limited. We believe that through its Operations Research Approach, NTI utilises most effectively its limited facilities towards the solution of India's tuberculosis problem.

The research which is foremostly needed in the poor countries of the world is not inventive and experimental research; the demand of these societies is no longer for new techniques and new inventions to improve their human material. Their demand is for systems composed of largely known techniques which could improve the human material to a level they can now afford and give the optimal utilisation of scarce economic resources. Research that satisfies this demand can be called application research or operations research. The term Operations Research has been borrowed from certain other fields i.e., military and industry. The techniques have mainly been developed during the second world war military field operations and later on applied in the field of industrial management. The spectacular progress of public health in the developed countries during the last century was a result of interaction mainly between economic progress and the development of science and not as a result of application of operations research. Over a period of time a very large number of inventions and experiences in techniques are available to apply in logical systems. This relative preponderance of technical knowledge over economic capacity is the social fact and many developing countries cannot choose the best and have to depend upon the utilisation of operations research in public health.

The following are the major seven phases in Operations Research applied to Public Health Services: i) formulation of the problem, ii) collection of data, iii) analysis and hypothesis formulation, iv) deriving solutions from the model, v) choosing the optimal solution and forecasting results, vi) the test run and the control system, vii) Recommending implementation. Operations Research can be a continuous process or even one time effort. For a country like India it could be a permanent feature of the national health services. The minimum composition of the Operations Research team is probably a public health administrator, an epidemiologist, a mathematician, a statistical and social scientist.

The essence of Operations Research is that logical thought combined with careful observation and methodological analysis, which should form the basis of decision making. Operations Research thus may be called as the science of common sense.

The objective of any research is to establish the truth. According to the subject which is being studied here, the following three levels of sciences can be distinguished: (i) The physical sciences which have their objective as non- living in nature. They include Astronomy, Physics, Chemistry etc. Their application in health includes technology of drugs and tools of diagnosis and treatment. (ii) The biological sciences deal with living things including human beings. Medical science represent an application of these sciences to the protection of health and the cure from diseases. (iii) The social sciences which have human society as their objective include Sociology, History, Economics. Their application to health problems is known as public health.

All three levels of sciences are linked. Disciplines which are situated on a higher level deal with much more complicated systems than disciplines on a lower level. There is also a difference in the levels of sophistication of the different systems coming within the scope of the same group of sciences. Less sophisticated systems are included in the more sophisticated and represent their sub systems. For instance, treatment is a sub system of the control of a communicable disease; sputum examination is a sub system of Case-finding etc. Research in health is being done on the basis of data collected by observation of real conditions or in experiments. The design of the experiment depends upon the complexity of the system under observation and on the possibility of observing one or more factors of the system (variables) after isolation or equalization of the other variables or in their full complexicity. In the field of physical sciences and technology there are very good possibilities for isolation of all variables except those which are under study. This is done in the simple testing of urine for the content of INH, or in similar tests. In medicine and biology it is impossible to isolate all variables without introducing bias; therefore a control group is needed in which all other factors (which are not being studied) are equalized. This is being done in controlled trials laboratory or clinical.

Epidemiologic observations are carried out with different tools; clinical (sputum or X-ray examination, tuberculin test); sociological (interview); physical (measurements), etc. They represent a method which is closer to real life, but they consider only one aspect (sub system) of a community health problem i.e., the trend of the disease without taking care of all other factors which play a role in the determination of this trend, such as economic and cultural variables, behaviour, health services etc. The highest level of research at present represents the systems analysis (operations research). This method has as its objective the study of all variables (or "key variables" at least) which are involved in a public health problem. Such a problem is being simulated by a system of functions (model) and "optimized" (solved) by a computer. The use of mathematics is necessary for the application of these four research methods.