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Published byEugenia Sutton Modified over 9 years ago
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A little VOCAB
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Causation is the "causal relationship between conduct and result". That is to say that causation provides a means of connecting conduct with a resulting effect, typically an injury Causation indicates that one event is the result of the occurrence of the other event; i.e. there is a causal relationship between the two events. This is also referred to as cause and effect. Causation
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In statistics, a confounding variable (also confounding factor, a confound, or confounder) is an extraneous variable in a statistical model that correlates (directly or inversely) with both the dependent variable and the independent variable. Confounding
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Non-linear Data Transforming Data to perform Linear Regression
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What to do if the data is not linear… Calculate the LSRL Is the residual plot scattered? NO Transform data: YES Appropriate model
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Let’s examine this data set. This shows the monthly premium for Jackson National’s 10-year Term Life Insurance Policy of $100,000 for males and females (smoker & non- smoker) at a given age.
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Looking at just the premium for males, we see that the data is not linear
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Separate LSRLs are fitted to different age ranges that have been transformed using logs Cool – it’s a piece-wise function!
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Example 1: Consider the average length and weight at different ages for Atlantic rockfish.
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Use your calculator to draw a scatterplot of the data for length (x), in L1 and weight (y), in L2. Is it linear? ____ Is there a pattern? _____ Since there is a pattern, let’s try to “straighten” the data.
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Since length is __ dimensional and weight (which depends on volume) is __ dimensional, let’s graph length 3 (x), in L3 vs. weight (y) in L2. Is the scatterplot linear? ____ Highlight L3 ENTER L1 ^ 3 ENTER
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Calculate the LSL on the transformed points (length 3, weight) and determine r 2.
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Predict the weight of an Atlantic Rockfish that is 31.5cm long.
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The residual clearly has a pattern, so we must transform it!
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