DO NOW 01/29 The data set below corresponds to ages within the city of Downtown Los Angeles: 26, 33, 35, 45, 27, 28, 29. From this data set, find the mean and standard deviation. WEIRD STUFF NORMAL DISTRIBUTIONS AND INTERVALS ENVIRONMENTAL STUDIES Today we will… Be able to describe what a normal distribution curve looks like. Understand how standard deviation relates to normal distribution STANDARD DEVIATION REVISITED We just learned about standard deviation Today we will be discussing what a normal distribution curve is and what it looks like. This is important because it allows us to look at our data and determine whether or not it looks “normal” or if it is “off” NORMAL DISTRIBUTION NORMAL DISTRIBUTION This curve says that 68% of our data will fall within 1 standard deviation above and below. 95% 2 standard deviations above and below. 99.7% of data fall 3 standard dev above and below THE MEAN. This curve just tells us what values fall within the average. If you’re within 1 standard deviation of the average, you are considered normal within the distribution. HEIGHTS AND ND Red= average Green= 68% NORMAL DISTRIBUTION STANDARD DEVIATION AND NORM. DIST. Sample standard deviation can either increase or decrease as a sample size gets larger. If your standard deviation is large, that means your values deviate largely from the mean. That means that your results deviate significantly from the mean of your sample, and thus are likely to not follow the normal distribution pattern we would normally expect to see. You want everything to be NORMAL!!! EXIT TICKET 1. What does the bell curve below show? Elaborate on what the standard deviations mean and the percentages. Give an example(s).