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Unformatted text preview: Lecture 8: Data and Summarizing Data Readings: Chapter 1, Chapter 2.1,2.2 Apr 6, 2012 1 Basic Concepts Statistics and Data Statistics : Statistics is the study of the collection, organization, analysis, and interpre- tation of data. It deals with all aspects of this, including the planning of data collection in terms of the design of surveys and experiments. Data : measurements from which information and knowledge are derived. Dataset : a collection of data, usually put in table form. Element : a single cellin a dataset. Observation : a subject on which data is being collected, makes up the rows of a dataset. Variable : any characteristic of an observation, makes up the columns of a dataset. Example of a dataset Types of data Categorical/Qualitative : places an individual into one of several groups (gender, eye color, college major,hometown,Level of satisfaction etc.) Nominal : order does NOT matter (gender, race, marital status) Ordinal : order DOES matter (Level of satisfaction, class [fresh, soph, jr, sr]) Continuous/Quantitative :attaches a numerical value to a variable so that adding or averaging the values makes sense (height, weight, age, income, yield, etc.) Interval : Differences are interpretable; no natural zero (SAT score). Ratio : Differences and ratios are interpretable; natural zero (height, weight, age). Excise 1 : What type of variable is... 1 Smoking status SAT score Income level of satisfaction GPA clothing size time it take to run a mile Cross-Sectional : Observes many subjects at the same time or approximately the same time. Time series : Observes one subject or many subjects over several time periods. Cross-Section Time Series Temperature of Jan 1 st in each state Temperature on the first of every month Profit of each store in Tippecanoe Mall earned on Black Friday Profit of a store for each day from Thanksgiving to Christmas Resting Hear rate of each person in class- room Heart rate before, during, and im- mediately after vigorous exercise Number of car accidents on Friday afternoon in each county of IN Number of car accidents each week- end of Football Season in West Lafayette 2 Ways to Get Data Sources of data Existing Sources : data that are there already exist. Surveys : Ask people their opinion or for any information. Experiments : deliberately imposes some treatment on individuals in order to observe their re- sponses (Make the individuals do something in particular) Observational Studies : investigators observe individuals and measure variables of in- terest without assigning treatments to the subjects. The treatment that each subject receives is determined beyond the control of the investigator....
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