Main objective of Tweed’s analysis:
**Core Concept**
Tweed's analysis is a statistical method used in epidemiology to calculate the attributable risk of a disease in a population. It involves comparing the incidence of a disease in an exposed group with that in an unexposed group. The main objective of Tweed's analysis is to quantify the association between a potential risk factor and the development of a disease.
**Why the Correct Answer is Right**
Tweed's analysis is used to calculate the population attributable risk (PAR) and the population attributable risk percentage (PAR%). The PAR represents the proportion of disease cases that can be attributed to a specific exposure, while the PAR% represents the percentage increase in disease risk associated with the exposure. By conducting Tweed's analysis, researchers can determine the extent to which a particular risk factor contributes to the incidence of a disease in a population.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Tweed's analysis is not primarily used to calculate the odds ratio (OR) or the relative risk (RR) of a disease. While these measures can be estimated from Tweed's analysis, they are not the main objectives of the method.
**Option B:** This option is incorrect because the main objective of Tweed's analysis is not to calculate the confidence interval (CI) of a disease incidence. While confidence intervals can be constructed from Tweed's analysis, they are not the primary focus of the method.
**Option C:** This option is incorrect because Tweed's analysis is not used to calculate the number needed to treat (NNT) or the number needed to harm (NNH). These measures are used in clinical trials to estimate the effectiveness of a treatment or the risk of harm associated with a particular intervention.
**Clinical Pearl / High-Yield Fact**
Tweed's analysis is a useful tool for epidemiologists and researchers who want to quantify the association between a potential risk factor and the development of a disease. By conducting Tweed's analysis, researchers can gain insights into the population attributable risk and the population attributable risk percentage, which can inform public health policy and disease prevention strategies.
**Correct Answer: C.**