QQ Plot

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QQ Plot - PowerPoint PPT Presentation

QQ Plot. Quantile to Quantile Plot Quantile: Points taken at regular intervals from the cumulative distribution function (CDF) of a random variable QQ Plot: Graphical method for comparing two probability distributions by plotting quantiles of their values against each other

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PowerPoint Slideshow about 'QQ Plot' - helmut

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Presentation Transcript
QQ Plot
• Quantile to Quantile Plot
• Quantile:
• Points taken at regular intervals from the cumulative distribution function (CDF) of a random variable
• QQ Plot:
• Graphical method for comparing two probability distributions by plotting quantiles of their values against each other
• Does not include spatial-temporal information

Wikipedia

Quantiles
• If the data set have 10 values of:
• 3, 6, 7, 8, 8, 10, 13, 15, 16, 20
• 4 quantiles would result in:
• 10 x ¼ = 2.5, rounded to 3 => 7
• 10 x ½ = 5 => 8
• 10 x ¾ = 7.5, rounded to 8 => 15
How could we do better?
• Integrate over space and time
• Use topographic surfaces as trends
Resampling
• Bootstrapping
• Drawing sets of samples, with replacement from the original dataset
• Different results each time
• Jackknifing
• Repeat the estimation leaving out part of the dataset each time
• Repeatable
• Work with any interpolation or trend-surface method