MDE Calculator Code

mde.js

 function ppnd(p) {
    a0 = 2.50662823884, a1 = -18.61500062529; a2 = 41.39119773534; a3 = -25.44106049637; b1=-8.47351093090; b2 = 23.08336743743; b3 = -21.06224101826; b4 = 3.13082909833; c0 = -2.78718931138; c1 = -2.29796479134; c2 = 4.85014127135; c3 = 2.32121276858; d1 = 3.54388924762; d2 = 1.63706781897;
    var r;
    var split = 0.42;
    var value;
    /*   0.08 < P < 0.92    */
    if (Math.abs(p-0.5)<=split){
        r=(p-0.5)*(p-0.5);
        value=(p-0.5)*(((a3*r+a2)*r+a1)*r+a0)/((((b4*r+b3)*r+b2)*r+b1)*r+1.0);
    }
    /* P < 0.08 or P > 0.92,
       R = min ( P, 1-P )   */
    else if(0.0<p && p<1.0){
        if(0.5<p) r=Math.sqrt(-Math.log(1.0-p));
        else r = Math.sqrt(-Math.log(p));
        value = (((c3*r+c2)*r+c1)*r+c0)/((d2*r+d1)*r+1.0);
        if(p<0.5)  value = - value;
    }
    /* P <= 0.0 or 1.0 <= P */
    else value = NaN;
    return value;
}

const dunnett_z = (p,tails,Variants)=>{
    var coefs=[];
    poly_rank=9;
    if(tails==1){
        coefs[1]=[-3.130385,55.34448,-715.9325,5235.129,-22224.02,57314.93,-91012.3,86844.54,-45632.87,10141.43];
        coefs[2]=[-2.434125,49.83425,-647.1348,4752.59,-20255.26,52422.9,-83508.44,79911.14,-42097.12,9377.248];
        coefs[3]=[-2.121302,47.82393,-621.974,4574.116,-19517.85,50567.02,-80625.85,77215.23,-40706.22,9073.262];
        coefs[4]=[-1.930303,46.77481,-608.8468,4480.195,-19125.93,49570.7,-79063.26,75740.3,-39938.61,8904.111];
        coefs[5]=[-1.796614,46.13057,-600.7998,4422.195,-18881.77,48944.54,-78072.93,74798.12,-39444.63,8794.507];
        coefs[6]=[-1.695463,45.69606,-595.3876,4382.92,-18715.08,48513.52,-77385.92,74139.77,-39097.16,8716.941];
        coefs[7]=[-1.61498,45.3845,-591.5205,4354.675,-18594.23,48198.57,-76880.19,73651.85,-38838.05,8658.774];
        coefs[8]=[-1.548647,45.15123,-588.6371,4333.479,-18502.82,47958.47,-76491.86,73274.75,-38636.62,8613.318];
        coefs[9]=[-1.492536,44.97085,-586.4174,4317.055,-18431.43,47769.48,-76184.04,72973.96,-38475.05,8576.677];
        coefs[10]=[-1.444115,44.82781,-584.6658,4304.008,-18374.25,47616.96,-75933.88,72728.01,-38342.24,8546.416];
    }
    if(tails==2){
        coefs[1]=[-0.01144596,4.352578,-90.54801,1004.088,-5580.947,17458.51,-32099.94,34391.93,-19857.28,4773.163];
        coefs[2]=[0.02111707,9.844298,-146.6649,1339.796,-6777.035,20060.73,-35576.61,37161.7,-21057.17,4988.887];
        coefs[3]=[0.09486066,13.24264,-189.4325,1619.879,-7834.534,22479.59,-38976.24,40026.06,-22382.01,5246.966];
        coefs[4]=[0.17702,14.85503,-210.8122,1761.529,-8369.46,23696.9,-40672.46,41438.68,-23025.83,5370.105];
        coefs[5]=[0.2539563,15.61456,-221.2075,1829.994,-8623.877,24262.83,-41438.35,42053.49,-23293.27,5418.251];
        coefs[6]=[0.3226849,15.96869,-226.2315,1862.437,-8740.18,24508.85,-41749.24,42280.26,-23378.88,5430.458];
        coefs[7]=[0.3834631,16.11954,-228.5149,1876.51,-8786.418,24593.83,-41833.31,42315.84,-23376.11,5425.477];
        coefs[8]=[0.4373194,16.16322,-229.3324,1880.803,-8795.706,24594.94,-41801.08,42255.2,-23329.85,5412.266];
        coefs[9]=[0.4853314,16.14836,-229.3371,1879.718,-8784.968,24551.47,-41708.48,42146.08,-23262.51,5395.257];
        coefs[10]=[0.5284387,16.10098,-228.8816,1875.627,-8763.279,24484.33,-41585.07,42013.49,-23185.67,5376.714];
    }
    var result=0;
    result=coefs[Variants-1][0];
    for(i=1;i<=poly_rank;i++){
        result+=coefs[Variants-1][i]*Math.pow(p,i);
    }
    if (Variants==2) return ppnd(1-(1-p)/tails); // regular ppnd for 2 variants case
    return result;
}

const fn=(p0,p1,za,zb)=>{
   return ((za+zb)**2*(p0+p1))/((p1-p0)**2);
}

function calcmde (n,p0,tails,variants,confidence,power,relative){
   var z_dunnett=dunnett_z(confidence,tails,variants);
   var z_beta=ppnd(power);
   var p1=p0;
   while(fn(p0,p1,z_dunnett,z_beta)>=n/variants) p1+=0.00001;
   var mde = 0;
   if(relative) {
       mde = (p1-p0)/p0;
   }
   else {
       mde = p1-p0;
   }
   var formatted_mde = (mde*100).toFixed(2);
   var result = {};
   result = {
       mde_raw: mde,
       mde: formatted_mde,
       status: 'ok'
   }
   return result;
}