Biostatistics I

The document serves as an educational resource for a course on biostatistics, outlining its fundamental principles and applications in the fields of biology, medicine, and public health. It begins by defining biostatistics as the application of statistical methods to solve biological problems, emphasizing the importance of statistical reasoning in scientific inquiry.

Key concepts discussed include the distinction between populations and samples, where a population refers to the entire group of observations, while a sample is a subset of that population. The document explains statistical inference as the process of drawing conclusions about a population based on sample data, highlighting the role of probability in making these inferences.

The text delves into probability distributions, defining them as descriptions of all possible outcomes and their associated probabilities. It explains the significance of z values in standard normal distribution and how they indicate the number of standard deviations a value is from the mean. The document also discusses when to use probability distributions, particularly in calculating confidence intervals and critical regions for hypothesis testing.

Another important topic covered is the difference between the t distribution and the z distribution, particularly in relation to sample size. The t distribution is used when the population standard deviation is unknown and the sample size is small, while the z distribution is applicable for larger samples. The concept of degrees of freedom is introduced, explaining its relevance in inferential statistics and its role in determining critical cutoff values for statistical tests.

The document also addresses how sample size affects estimation, noting that larger sample sizes lead to more precise estimates and narrower confidence intervals. It outlines a three-step process for calculating the necessary sample size to achieve a desired confidence interval for a population mean.

In conclusion, the document emphasizes the importance of biostatistics in generating hypotheses, designing studies, and analyzing data to draw meaningful conclusions in the context of public health and biological research. It serves as a foundational guide for students and professionals seeking to understand and apply statistical methods in their work.