STAT-2126EL Lecture Notes - Lecture 10: Dear Abby, Binomial Distribution, Standard Deviation
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Lecture 10: a normal distribution is symmetrical, 50% of the scores are above the mean and 50% are below the mean, the majority of scores are clustered around the mean. Why do things in nature follow the normal distribution: let"s look at something called the binomial distribution, tossing coins is an easy way to visualize the binomial distribution. In this case, the probability of each outcome occurring is 50%. Probability and the normal distribution: convert score to z-score and then look on table to see the probability, x z-score probability. Dear abby example: mother wants to know if it is possible to have a baby born 10 months after conception, let"s see how likely this was to occur. Answer in notebook: percentile rank also called a percentile is the score expressed as a percent of scores that fall above or below it.