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Summarizing quantitative data

Measuring center in quantitative data

Learn
Statistics intro: Mean, median, & mode
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Mean, median, & mode example
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Calculating the mean
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Choosing the "best" measure of center
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Mean, median, and mode review
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Practice
Mean, median, and modeGet 5 of 7 questions to level up!
Calculating the meanGet 3 of 4 questions to level up!
Calculating the medianGet 3 of 4 questions to level up!

More on mean and median

Learn
Comparing means of distributions
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Means and medians of different distributions
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Impact on median & mean: removing an outlier
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Impact on median & mean: increasing an outlier
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Mean as the balancing point
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Missing value given the mean
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Median & range puzzlers
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Practice
Calculating the mean: data displaysGet 3 of 4 questions to level up!
Calculating the median: data displaysGet 3 of 4 questions to level up!
Effects of shifting, adding, & removing a data pointGet 3 of 4 questions to level up!
Missing value given the meanGet 3 of 4 questions to level up!
Median & range puzzlersGet 3 of 4 questions to level up!

Interquartile range (IQR)

Learn
Interquartile range (IQR)
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Comparing range and interquartile range (IQR)
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Interquartile range review
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Practice
Interquartile range (IQR)Get 3 of 4 questions to level up!

Variance and standard deviation of a population

Learn
Measures of spread: range, variance & standard deviation
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Variance of a population
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Population standard deviation
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The idea of spread and standard deviation
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Calculating standard deviation step by step
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Mean and standard deviation versus median and IQR
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Concept check: Standard deviation
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Statistics: Alternate variance formulas
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Practice
Standard deviation of a populationGet 3 of 4 questions to level up!

Variance and standard deviation of a sample

Learn
Sample variance
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Sample standard deviation and bias
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Population and sample standard deviation review
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Practice
VarianceGet 3 of 4 questions to level up!
Sample and population standard deviationGet 3 of 4 questions to level up!

More on standard deviation

Learn
Why we divide by n - 1 in variance
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Simulation showing bias in sample variance
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Simulation providing evidence that (n-1) gives us unbiased estimate
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Unbiased estimate of population variance
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Review and intuition why we divide by n-1 for the unbiased sample variance
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Box and whisker plots

Learn
Worked example: Creating a box plot (odd number of data points)
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Worked example: Creating a box plot (even number of data points)
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Constructing a box plot
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Reading box plots
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Interpreting box plots
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Box plot review
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Judging outliers in a dataset
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Identifying outliers with the 1.5xIQR rule
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Practice
Creating box plotsGet 3 of 4 questions to level up!
Reading box plotsGet 3 of 4 questions to level up!
Interpreting quartilesGet 3 of 4 questions to level up!
Identifying outliersGet 3 of 4 questions to level up!

Other measures of spread

Learn
Range and mid-range
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Mean absolute deviation (MAD)
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Mean absolute deviation example
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Mean absolute deviation (MAD) review
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Practice
Mean absolute deviation (MAD)Get 3 of 4 questions to level up!

About this unit

This unit covers common measures of center like mean and median. We'll also learn to measure spread or variability with standard deviation and interquartile range, and use these ideas to determine what data can be considered an outlier.