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This lecture provides an introduction to the Central Limit Effect (CLE) and its significance in statistics. The CLE describes how the sum of a large number of independent random variables tends to follow a normal distribution, regardless of the original distributions of the variables. Key aspects covered include the properties of the normal distribution, specifically the empirical rule (68%, 95%, 99.7%) for standard deviations, and the challenge of summing random variables. A thorough grasp of the CLE is essential for statistical analysis and inference.
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Statistics: Continuous Methods STAT 452/652 Fall 2008 Lecture 3: Central Limit Effect (slides only contain intro)
Normal distribution 68% 95% 99.7%
Summing random variables B A A+B
Summing random variables A, B, C, D A+B A+B+C+D A+B+C
Summing random variables Generally, summation changes the shape of the distribution: number of possible values, spread, mean, etc. There is no simple way to tell what is the distribution of A+B if we know A and B (that is, you HAVE to do some integration and stuff) ... and what about A+B+C+...+Z? We need a miracle to cope with this...
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