University:
Winston-Salem Forsyth County Schools
Course:
AP Statistics
Academic year:

2014
Views:

74

Pages:

1
Author:

Rylee Roach

Descriptive Statistics Descriptive Statistics 14.4 Measures of Spread 29 28 Descriptive Statistics Conclusion Descriptive Statistics 30 The Standard Deviation of a Data Set Let A denote the mean of the data set. For each number x in the data set, compute its deviation from the mean (x – A), and square each of these numbers. These are called the squared deviations. Find the average of the squared deviations. This number is called the variance V. The standard deviation is the square root of the variance ( σ = V ). Range The difference between the highest and lowest values of the data and is denoted by R. Thus, R = Max - Min. Interquartile Range The difference between the third quartile and the first quartile (IQR = Q3 – Q1), and it tells us how spread out the middle 50% of the data values are. Basic concepts in statistics Graphical summaries Numerical summaries 31 1