Introduction to Biostatistics

Definitions and Scope of Statistics

  • Statistics: The mathematical and scientific methods used to collect, organize, summarize, present, and analyze numerical data in order to draw conclusions and make decisions.

  • Key Theoretical Definitions:

    • "The mathematics of experimentation" (K. Mather).

    • "The scientific study of numerical data describing natural variations" (Sokal & Rohlf, 1981).

  • Biostatistics: The application of statistical methods to biological, medical, and health data to enable decision-making under conditions of uncertainty.

  • Applications: Medicine (disease frequency, treatment efficacy, screening), Geophysics (weather forecasting, climatology, pollution), Demography (population censuses), Economics and social sciences, Sociology, Marketing (opinion polling), and Physics.

Branches of Biostatistics

Branches of biostatistics: descriptive statistics versus inferential statistics

  • Descriptive Statistics: Involves collecting, organizing, summarizing, and presenting data to describe a set according to specific criteria.

  • Inferential Statistics: Involves inferring unknown population characteristics from a representative sample with a margin of error; includes hypothesis testing, determining relationships, and making predictions.

The Statistical Approach

  • Data Collection:

    • Identification of study characteristics.

    • Defining the target group via a comprehensive survey (total population) or a partial survey (sample).

    • Establishing protocols (who does what, how, and when).

    • Data pre-processing and transformation.

  • Data Processing:

    • Output of quantitative series and figures.

    • Exploitation through classification and visual or numerical summarization.

  • Inferential Tools:

    • Hypothesis Testing: Formulating null versus alternative hypotheses.

    • Estimation: Using confidence intervals and pp-values (probability of observing the result if the null hypothesis is true).

    • Statistical Tests: tt-test, chi-square, ANOVA, and regression.

Biological and Metrological Variability

  • Nature of Biology: An observational, non-exact science where variability is a fundamental characteristic.

  • Components of Global Variability:

    • Biologic Variability: Subdivided into intra-individual variability and inter-individual variability.

    • Metrological Variability: Subdivided into experimental variability and variability caused by the measuring device.