Stats Prelim 1 - of the data Scatterplots the most useful...

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Two variables on the same cases are associated if knowing the value of one of the variables tells you something about the vales of the other variables that you would not know without information. Strong association : Knowing the size of a coffee cup tells us the exact price Weak association: Although smokers on average die earlier than nonsmokers, some smokers live until their 90s. Thus, someone who smokes is merely in a group of people that are more likely to die at a younger age Response variable- measures an outcome of a study. Explanatory variable- explains or causes change in the response variable Changes in explanatory variables cause a change in response variables Explanatory = independent Response = dependent Guiding Principles: 1. Start with a graphical display 2. Look for overall patterns and deviations from those patterns 3. Based on what you see, use numerical summaries to describe specific aspects
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Unformatted text preview: of the data Scatterplots the most useful graph for displaying the relationship between two quantitative variables. The value of one variable appears on the horizontal axis, the value of the other variable appears on the vertical axis. Each dot represents an individuals responses Explanatory (independent) variable goes on the X-axis and response (dependent) variable on Y Axis Clusters in a graph suggest that the data describe several distinct kinds of individuals (SAT vs. ACT) Positive Association- occurs when above average values of one variable tend to accompany above average values of the other. Negative Association- when above average values of one accompany below average values of the other The strength of a relationship is determined by how closely the points follow a clear form (linear). How close the points are to the line of best fit...
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This note was uploaded on 10/16/2008 for the course PAM 2100 taught by Professor Abdus,s. during the Fall '08 term at Cornell University (Engineering School).

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