표준편차 계산기의 신뢰구간
- n:샘플 크기
- s 2 : 표본 분산
- X 2 : 자유도가 n-1인 카이제곱의 임계값
95 % CI = [ 5.0637 , 8.8119 ]
function calc() {
//get input values var n = +document.getElementById('n').value; var s = +document.getElementById('s').value; var conf = +document.getElementById('conf').value;
var s2 = Math.pow(s,2); var df = n-1; var confUse = 1-conf; var confOut = conf*100;
var x2high = jStat.chisquare.inv(confUse/2, df); var x2low = jStat.chisquare.inv(1-(confUse/2), df);
//calculate stuff var low = Math.sqrt(df*s2/x2low); var high = Math.sqrt(df*s2/x2high);
//output results document.getElementById('confOut').innerHTML = confOut; document.getElementById('confOut2').innerHTML = confOut; document.getElementById('low').innerHTML = low.toFixed(4); document.getElementById('low2').innerHTML = low.toFixed(4); document.getElementById('high').innerHTML = high.toFixed(4); document.getElementById('high2').innerHTML = high.toFixed(4); }