ztable
Version:
Convert z-scores to a percentiles.
84 lines (73 loc) • 4.42 kB
JavaScript
var ZTABLE =
{
'z': [0.09, 0.08,0.07,0.06,0.05,0.04,0.03,0.02,0.01,0],
'-3.4': [ 0.0002, 0.0003, 0.0003, 0.0003, 0.0003, 0.0003, 0.0003, 0.0003, 0.0003, 0.0003],
'-3.3': [ 0.0003, 0.0004, 0.0004, 0.0004, 0.0004, 0.0004, 0.0004, 0.0005, 0.0005, 0.0005],
'-3.2': [ 0.0005, 0.0005, 0.0005, 0.0006, 0.0006, 0.0006, 0.0006, 0.0006, 0.0007, 0.0007],
'-3.1': [ 0.0007, 0.0007, 0.0008, 0.0008, 0.0008, 0.0008, 0.0009, 0.0009, 0.0009, 0.0010],
'-3.0': [ 0.0010, 0.0010, 0.0011, 0.0011, 0.0011, 0.0012, 0.0012, 0.0013, 0.0013, 0.0013],
'-2.9': [ 0.0014, 0.0014, 0.0015, 0.0015, 0.0016, 0.0016, 0.0017, 0.0018, 0.0018, 0.0019],
'-2.8': [ 0.0019, 0.0020, 0.0021, 0.0021, 0.0022, 0.0023, 0.0023, 0.0024, 0.0025, 0.0026],
'-2.7': [ 0.0026, 0.0027, 0.0028, 0.0029, 0.0030, 0.0031, 0.0032, 0.0033, 0.0034, 0.0035],
'-2.6': [ 0.0036, 0.0037, 0.0038, 0.0039, 0.0040, 0.0041, 0.0043, 0.0044, 0.0045, 0.0047],
'-2.5': [ 0.0048, 0.0049, 0.0051, 0.0052, 0.0054, 0.0055, 0.0057, 0.0059, 0.0060, 0.0062],
'-2.4': [ 0.0064, 0.0066, 0.0068, 0.0069, 0.0071, 0.0073, 0.0075, 0.0078, 0.0080, 0.0082],
'-2.3': [ 0.0084, 0.0087, 0.0089, 0.0091, 0.0094, 0.0096, 0.0099, 0.0102, 0.0104, 0.0107],
'-2.2': [ 0.0110, 0.0113, 0.0116, 0.0119, 0.0122, 0.0125, 0.0129, 0.0132, 0.0136, 0.0139],
'-2.1': [ 0.0143, 0.0146, 0.0150, 0.0154, 0.0158, 0.0162, 0.0166, 0.0170, 0.0174, 0.0179],
'-2.0': [ 0.0183, 0.0188, 0.0192, 0.0197, 0.0202, 0.0207, 0.0212, 0.0217, 0.0222, 0.0228],
'-1.9': [ 0.0233, 0.0239, 0.0244, 0.0250, 0.0256, 0.0262, 0.0268, 0.0274, 0.0281, 0.0287],
'-1.8': [ 0.0294, 0.0301, 0.0307, 0.0314, 0.0322, 0.0329, 0.0336, 0.0344, 0.0351, 0.0359],
'-1.7': [ 0.0367, 0.0375, 0.0384, 0.0392, 0.0401, 0.0409, 0.0418, 0.0427, 0.0436, 0.0446],
'-1.6': [ 0.0455, 0.0465, 0.0475, 0.0485, 0.0495, 0.0505, 0.0516, 0.0526, 0.0537, 0.0548],
'-1.5': [ 0.0559, 0.0571, 0.0582, 0.0594, 0.0606, 0.0618, 0.0630, 0.0643, 0.0655, 0.0668],
'-1.4': [ 0.0681, 0.0694, 0.0708, 0.0721, 0.0735, 0.0749, 0.0764, 0.0778, 0.0793, 0.0808],
'-1.3': [ 0.0823, 0.0838, 0.0853, 0.0869, 0.0885, 0.0901, 0.0918, 0.0934, 0.0951, 0.0968],
'-1.2': [ 0.0985, 0.1003, 0.1020, 0.1038, 0.1056, 0.1075, 0.1093, 0.1112, 0.1131, 0.1151],
'-1.1': [ 0.1170, 0.1190, 0.1210, 0.1230, 0.1251, 0.1271, 0.1292, 0.1314, 0.1335, 0.1357],
'-1.0': [ 0.1379, 0.1401, 0.1423, 0.1446, 0.1469, 0.1492, 0.1515, 0.1539, 0.1562, 0.1587],
'-0.9': [ 0.1611, 0.1635, 0.1660, 0.1685, 0.1711, 0.1736, 0.1762, 0.1788, 0.1814, 0.1841],
'-0.8': [ 0.1867, 0.1894, 0.1922, 0.1949, 0.1977, 0.2005, 0.2033, 0.2061, 0.2090, 0.2119],
'-0.7': [ 0.2148, 0.2177, 0.2206, 0.2236, 0.2266, 0.2296, 0.2327, 0.2358, 0.2389, 0.2420],
'-0.6': [ 0.2451, 0.2483, 0.2514, 0.2546, 0.2578, 0.2611, 0.2643, 0.2676, 0.2709, 0.2743],
'-0.5': [ 0.2776, 0.2810, 0.2843, 0.2877, 0.2912, 0.2946, 0.2981, 0.3015, 0.3050, 0.3085],
'-0.4': [ 0.3121, 0.3156, 0.3192, 0.3228, 0.3264, 0.3300, 0.3336, 0.3372, 0.3409, 0.3446],
'-0.3': [ 0.3483, 0.3520, 0.3557, 0.3594, 0.3632, 0.3669, 0.3707, 0.3745, 0.3783, 0.3821],
'-0.2': [ 0.3829, 0.3897, 0.3936, 0.3974, 0.4013, 0.4052, 0.4090, 0.4129, 0.4168, 0.4207],
'-0.1': [ 0.4247, 0.4286, 0.4325, 0.4364, 0.4404, 0.4443, 0.4483, 0.4522, 0.4562, 0.4602],
'0.0': [ 0.4641, 0.4681, 0.4721, 0.4761, 0.4801, 0.4840, 0.4880, 0.4920, 0.4960, 0.5000]
};
module.exports = function (zscore) {
zscore = parseFloat(zscore);
if (isNaN(zscore)) {
throw new TypeError('zscore is not a valid number');
}
var yZscore = -3.4;
var xZscore = 0.09;
if(zscore === 0) {
return 0.5000;
}
if(zscore > 0) {
if(zscore > 3.49) {
return 1;
}
zscore = Math.floor(zscore * 100) / 100;
yZscore = Math.floor(zscore * 10) / 10;
yZscore = -yZscore;
} else {
if(zscore < -3.49) {
return 0;
}
zscore = Math.ceil(zscore * 100) / 100;
yZscore = Math.ceil(zscore * 10) / 10;
}
xZscore = Math.abs(Math.round((zscore % yZscore) * 10000) / 10000);
var z100 = isNaN(xZscore) ? Math.abs(zscore) : xZscore;
var z10 = yZscore === 0 ? '0.0' : yZscore.toFixed(1);
var col = ZTABLE.z.indexOf(z100);
var perc = ZTABLE[z10][col];
if(zscore > 0) {
perc = Math.round((1 - perc) * 10000) / 10000;
}
return perc;
};