Biostatistics II: data, variables and measurement

Biostatistics is part and parcel of biomedical research. The data from biomedical studies require statistical treatment for its effective presentation and correct interpretation. The choice of appropriate statistical methods to be applied depends upon the kind of data and variables. Different types of variables (characteristics) generate different types of data. Variables can be classified in many ways; qualitative and quantitative, nominal and ordinal or discrete and continuous. Different measurement scales are used to measure different types of variables; nominal ordinal scales for qualitative and interval ratio scale for quantitative variables. Different statistical methods/tests are employed for presentation and analysis of different types of data. For qualitative data; percentage, proportions, rate, ratios, standard error of proportions, chi-square test etc. are applied. While mean, range, standard deviation, coefficient of variation, correlation coefficient, etc. are employed in case of quantitative data. This article, second of the series, describes various types of data, variables and measurement scales. Learning objective At the completion of this article, the reader should have a clear understanding of different types of data, variables and their measurement scales, and be able to utilize these concepts in organizing the research of his own and for interpreting the results of other studies