STA6126 Chapter 1 & 2

STA6126 Chapter 1 & 2 - Revised on November 9, 2011...

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Revised on November 9, 2011 Chapter 1 Descriptive and Inferential Statistics Statistics is the science of Collecting Classifying Analyzing Generalizing a set of data obtained for a special purpose. Why study statistics? Statistics provides methods for Design: planning how to gather data for research studies (Chapter 2) Description: Summarizing the data collected in ways that are easy to understand (Chapter 3) Inference: Making decisions about the population using information in the sample. (Chapters 5 – 16) Probabilistic Reasoning: All statistical techniques are based on probabilistic reasoning (Chapter 4) Data is a collection of observations o On one or more characteristic(s) of interest [ random variable (s)] o On population units (giving population data) or o On selected sample units (giving sample data). We collect data by o Sample surveys or o Experiments or o Censuses STA 6126 Chapters 1 & 2, page 1
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Once data is collected, the first step is to use Descriptive Statistics or Exploratory Data Analysis (EDA) [ first proposed by J. W. Tukey (1977) of Princeton University] for summarizing the data using tables, graphs and numerical summaries. Statistical Inference is our main goal in sample surveys and experiments. Statistical inference is the process of making decision about one or more population parameter(s) using one or more sample statistic(s). Observe that for census data there is no need to use inferential statistics. [Why?] A parameter is a numerical summary of the population data . Most frequently used ones are the population mean (μ), the population standard deviation (σ), and the population variance (σ 2 ) and population proportion ( π ). In general population parameters are shown by lower case Greek letters. A
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STA6126 Chapter 1 & 2 - Revised on November 9, 2011...

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