function calculateDelta()

in assets/android-metrics.js [61:87]

• 20 lines of code
• 2 McCabe index (conditional complexity)

function calculateDelta(values) {
    const n = values.length;
    
    // Create x values (0 to n-1) representing the time sequence of data points
    const xValues = Array.from({ length: n }, (_, i) => i);

    // Calculate the averages of x and y (the subset values)
    const xAvg = xValues.reduce((sum, x) => sum + x, 0) / n;
    const yAvg = values.reduce((sum, y) => sum + y, 0) / n;

    // Calculate the slope (m) of the line of best fit using the least squares method
    const numerator = xValues.reduce((sum, x, i) => sum + (x - xAvg) * (values[i] - yAvg), 0);
    const denominator = xValues.reduce((sum, x) => sum + Math.pow(x - xAvg, 2), 0);
    const slope = numerator / denominator;

    // Calculate the y-intercept (b) of the line of best fit
    const intercept = yAvg - slope * xAvg;

    // Calculate the predicted y-values (trend line) for the first and last x-values
    const firstY = intercept;  // y-value at x = 0 (first data point)
    const lastY = slope * (n - 1) + intercept;  // y-value at x = n - 1 (last data point)

    // Calculate the percentage improvement between the first and last points on the trend line
    const improvement = ((lastY - firstY) / firstY) * 100;
    
    return improvement.toFixed(2);
}