SRMP_Statistics.pdf

# H o w t o f i n d t h e m e a n the mean is just the

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H O W T O F I N D T H E M E A N The mean is just the _____________________________ of the numbers. It is easy to calculate: Just add up all the numbers, then divide by how many numbers there are. (In other words it is the sum divided by the count.) Activity 1: What is the mean of your leaves? Are there different localities that you need to average and compare? Complete the sentences below. The sum of these numbers is equal to ________ and there are ________ numbers. The mean of the numbers is ________.

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Science Research Mentoring Program STATISTICS © 2013 American Museum of Natural History. All Rights Reserved. 16 WORKSHEET: Morphometrics and Basic Statistics (continued) S T A N D A R D D E V I A T I O N & VA R I A N C E The Standard Deviation ( σ ) is a measure of how ______________________ numbers are. The formula is easy: it is the square root of the Variance. So now you ask, “What is the Variance?” The Variance (which is the square of the standard deviation, ie: σ 2 ) is defined as the average of the squared differences from the Mean. Let’s begin with an example. Activity 4: You and your friends have just measured the heights of your dogs (in millimeters): 1. 1. Calculate the Mean for the dogs below (their heights are underneath the graph). 2. 2. Now, for each number subtract the Mean and then square the result (the squared difference). 3. Find the average of those squared differences. (Why Square?) The heights (at the shoulders) are: 600mm, 470m, 170mm, 430mm, and 300mm. Mean = __________

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Science Research Mentoring Program STATISTICS © 2013 American Museum of Natural History. All Rights Reserved. 17 WORKSHEET: Morphometrics and Basic Statistics (continued) S T A N D A R D D E V I A T I O N & VA R I A N C E ( C O N T I N U E D ) Now, we calculate each dogs’ difference from the Mean: To calculate the Variance, take each difference, square it, and then average the result: Variance: σ 2 = So, the Variance is ___________________.
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• Fall '17
• Statistics, Natural history, American Museum of Natural History, American Museum, Science Research

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