Statistics Demo Experiment

### Statistics

Jaap Murre

Demo of built-in statistics functions

There are a number of built-in basic statistics functions, such as mean and variance. These take an array of numbers as argument and return a single Number value. To avoid confusion with other functions, they must always be prefixed with stat, as in stat.mean(arr), where arr is an array of Numbers.

• stat.mean()
• Average
• stat.median()

• Median
• stat.stddev()

• Standard deviation
• stat.stderr()

• Standard error
• stat.variance()

• Variance
• stat.sumsqerr()

• Sum of squared errors (i.e., sume of squared deviations from mean)
• stat.min()

• Lowest value
• stat.max()

• Highest value
• stat.range()

• Difference between highest and lowest value

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```var arr = [2,1,4,6,1,3],
arr_m = stat.mean(arr),
arr_sd = stat.stddev(arr);

// Use toFixed(n) to convert a Number to text with n decimals
// Don't use it before further calculations as it returns a text string
text("Average: " + arr_m.toFixed(2));
await(2000);
text("Standard Dev: " + arr_sd.toFixed(2));
await(2000);

/*

The following functions take an array as an argument and return one value

stat.mean()
Average

stat.median()
Median

stat.stddev()
Standard deviation

stat.stderr()
Standard error

stat.variance()
Variance

stat.sumsqerr()
Sum of squared errors (i.e., sume of squared deviations from mean)

stat.min()
Lowest value

stat.max()
Highest value

stat.range()
Difference between highest and lowest value

*/

// Square root, sin, round, etc. are already in Javascript in the Math library
// E.g., see https://www.w3schools.com/js/js_math.asp

var x = Math.sqrt(100);

text("sqrt(100): " + x);
await(2000);```

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