Page 11 - Statistics for Dummies

Table of Contents
Distribution and normal distribution ................................................54
Central Limit Theorem ........................................................................55
z-values .................................................................................................56
Experiments ..........................................................................................56
Surveys (Polls) .....................................................................................58
Margin of error .....................................................................................58
Confi dence interval ..............................................................................59
Hypothesis testing ...............................................................................60
p-values .................................................................................................61
Statistical signifi cance .........................................................................61
Correlation versus causation .............................................................63
Part II: Number-Crunching Basics ............................... 65
Chapter 5: Means, Medians, and More . . . . . . . . . . . . . . . . . . . . . . . . . .67
Summing Up Data with Descriptive Statistics ............................................67
Crunching Categorical Data: Tables and Percents ....................................68 ix
Measuring the Center with Mean and Median ...........................................71
Averaging out to the mean .................................................................71
Splitting your data down the median ................................................73
Comparing means and medians: Histograms ...................................74
Accounting for Variation ..............................................................................76
Reporting the standard deviation ......................................................77
Being out of range ................................................................................80
Examining the Empirical Rule (68-95-99.7) .................................................81
Measuring Relative Standing with Percentiles ...........................................84
Calculating percentiles ........................................................................84
Interpreting percentiles ......................................................................85
Gathering a fi ve-number summary ....................................................89
Exploring interquartile range .............................................................90
Chapter 6: Getting the Picture: Graphing Categorical Data. . . . . . . . .91
Take Another Little Piece of My Pie Chart .................................................92
Tallying personal expenses ................................................................92
Bringing in a lotto revenue .................................................................92
Ordering takeout ..................................................................................94
Projecting age trends ..........................................................................95
Raising the Bar on Bar Graphs .....................................................................97
Tracking transportation expenses.....................................................97
Making a lotto profi t ............................................................................99
Tipping the scales on a bar graph ...................................................100
Pondering pet peeves ........................................................................101

3/25/11 8:18 PM
02_9780470911082-ftoc.indd ix 3/25/11 8:18 PM
02_9780470911082-ftoc.indd ix