Community physician takes action based on :

Ans is 'a' i.e. Population attributable risk Attributable risk = 100 x (Incidence of disease rate among exposed-incidence of diseases rate among not exposed) / (Incidence of diseases rate among exposed)Attributable risk indicates to what extent the disease under study can be attributed to the exposure.Population attributable risk (PAR) = 100 x (Incidence of diseases in the total population-incidence of diseases among those not exposed to causal factor) / (Incidence of diseases in the total population)PAR provides an estimate of the amount by which the disease could be reduced in that population if the suspected factor was eliminated or modified. For e.g. , 86% is the PAR, then 86% of deaths from lung cancer could be avoided if the risk factor of cigarettes were eliminated.Thus we see that the best indices for community physicians would be PAR because they have to take care of the whole population. From PAR they come to know clearly how much of a disease could be wiped out by a particular action.