Statistics and the Scientific Method Chapter 1 Statistics and the Scientific Method

Introduction Applied Statistics generalizes into 4-step process: Problem Definition/Description Data Collection Data Description/Summarization Data Analysis/Interpretation/Communication Many methods exist to complete this process for many types of data and experimental settings

Examples of Practical Problems New Drug Testing: Does a new drug improve patient condition more so than an existing drug or placebo? Quality Control: Does a manufacturing facility continue to have an acceptable rate of defectives? Political Polling: What proportion of adults favor a particular political stance or candidate? Measuring Animal Poulations: How many fish of a particular species live in a lake? Agricultural Production: Which of 4 varieties of fertilizer give best results in grain production? Marketing: What levels of pricing and advertising produce the highest profits for a new product?

Populations and Samples Population: All measurements of interest to researcher Sample: Subset of population that is obtained and to be analyzed Population Sample

Statistical Inference Goal: Make statements regarding a population (or true state of nature) based on observations from a sample. What can be said of the average measurement in a population, when we obtain the average of a sample from the population? Can we conclude success rates differ for two treatments in nature (across a conceptual population of units), based on a certain difference in success rates in two samples of units that were assigned the treatments