Calculateur de test de Bartlett
Le test de Bartlett est utilisé pour tester si les échantillons proviennent de populations présentant des variances égales. Certains tests statistiques, comme l’ ANOVA unidirectionnelle , supposent que les variances sont égales entre les échantillons. Le test de Bartlett peut être utilisé pour vérifier cette hypothèse.
Pour effectuer un test de Bartlett sur un maximum de cinq échantillons, entrez simplement les valeurs des données ci-dessous et cliquez sur le bouton « Calculer ». Une statistique de test et la valeur p correspondante seront présentées ci-dessous. Une valeur p inférieure à 0,05 constitue une preuve solide que les variances ne sont pas égales entre les échantillons.
//create function that performs t test calculations function calc() {
//define addition function function add(a, b) { return a + b; }
//get raw data //group a // var values_a_input = document.getElementsByClassName('a'); //var values_a_array = []; //for (var i = 0; i < values_a_input.length; i++) { // values_a_array[i] = values_a_input[i].innerText; // } //values_a_array = values_a_array.filter(n => n); //var group_a = values_a_array.map(Number); if(document.getElementById("a").value == '') { var group_a = ''; } else { var group_a = document.getElementById('a').value.match(/\d+/g).map(Number); }
if(document.getElementById("b").value == '') { var group_b = ''; } else { var group_b = document.getElementById('b').value.match(/\d+/g).map(Number); }
if(document.getElementById("c").value == '') { var group_c = ''; } else { var group_c = document.getElementById('c').value.match(/\d+/g).map(Number); }
if(document.getElementById("d").value == '') { var group_d = ''; } else { var group_d = document.getElementById('d').value.match(/\d+/g).map(Number); }
if(document.getElementById("e").value == '') { var group_e = ''; } else { var group_e = document.getElementById('e').value.match(/\d+/g).map(Number); }
var all_groups = (group_a.concat(group_b, group_c, group_d, group_e)).filter(n => n);
//get summary stats of each group if (group_a.length > 0) { var mean_group_a = math.mean(group_a); }; if (group_b.length > 0) { var mean_group_b = math.mean(group_b); }; if (group_c.length > 0) { var mean_group_c = math.mean(group_c); }; if (group_d.length > 0) { var mean_group_d = math.mean(group_d); }; if (group_e.length > 0) { var mean_group_e = math.mean(group_e); };
if (group_a.length > 0) { var var_group_a = math.var(group_a); }; if (group_b.length > 0) { var var_group_b = math.var(group_b); }; if (group_c.length > 0) { var var_group_c = math.var(group_c); }; if (group_d.length > 0) { var var_group_d = math.var(group_d); }; if (group_e.length > 0) { var var_group_e = math.var(group_e); };
if (group_a.length > 0) { var lnvar_group_a = Math.log(var_group_a); } else { var lnvar_group_a = 0;}; if (group_b.length > 0) { var lnvar_group_b = Math.log(var_group_b); } else { var lnvar_group_b = 0;}; if (group_c.length > 0) { var lnvar_group_c = Math.log(var_group_c); } else { var lnvar_group_c = 0;}; if (group_d.length > 0) { var lnvar_group_d = Math.log(var_group_d); } else { var lnvar_group_d = 0;}; if (group_e.length > 0) { var lnvar_group_e = Math.log(var_group_e); } else { var lnvar_group_e = 0;};
if (group_a.length > 0) { var df_group_a = group_a.length-1; } else { var df_group_a = 0;}; if (group_b.length > 0) { var df_group_b = group_b.length-1; } else { var df_group_b = 0;}; if (group_c.length > 0) { var df_group_c = group_c.length-1; } else { var df_group_c = 0;}; if (group_d.length > 0) { var df_group_d = group_d.length-1; } else { var df_group_d = 0;}; if (group_e.length > 0) { var df_group_e = group_e.length-1; } else { var df_group_e = 0;};
var total_df = [df_group_a, df_group_b, df_group_c, df_group_d, df_group_e].reduce(add, 0); var total_df1 = 1 / total_df;
var lnvar_array = [lnvar_group_a, lnvar_group_b, lnvar_group_c, lnvar_group_d, lnvar_group_e]; var df_array = [df_group_a, df_group_b, df_group_c, df_group_d, df_group_e]; var lnvar_df_array = [] for (var i = 0; i < lnvar_array.length; i++) { lnvar_df_array.push(lnvar_array[i] * df_array[i]); } var sum_lnvar_df_array = lnvar_df_array.reduce(add, 0); if (group_a.length > 0) { var flag_group_a = 1; } else { var flag_group_a = 0;}; if (group_b.length > 0) { var flag_group_b = 1; } else { var flag_group_b = 0;}; if (group_c.length > 0) { var flag_group_c = 1; } else { var flag_group_c = 0;}; if (group_d.length > 0) { var flag_group_d = 1; } else { var flag_group_d = 0;}; if (group_e.length > 0) { var flag_group_e = 1; } else { var flag_group_e = 0;};
if (group_a.length > 0) { var df1_group_a = 1/df_group_a; } else { var df1_group_a = 0;}; if (group_b.length > 0) { var df1_group_b = 1/df_group_b; } else { var df1_group_b = 0;}; if (group_c.length > 0) { var df1_group_c = 1/df_group_c; } else { var df1_group_c = 0;}; if (group_d.length > 0) { var df1_group_d = 1/df_group_d; } else { var df1_group_d = 0;}; if (group_e.length > 0) { var df1_group_e = 1/df_group_e; } else { var df1_group_e = 0;};
var df1_array = [df1_group_a, df1_group_b, df1_group_c, df1_group_d, df1_group_e]; var df1_array_sum = df1_array.reduce(add, 0);
var treatments = [flag_group_a, flag_group_b, flag_group_c, flag_group_d, flag_group_e].reduce(add, 0) - 1;
if (treatments == 1) { var total_var = jStat.pooledvariance([group_a, group_b]); var total_lnvar = Math.log(total_var); } else if (treatments == 2) { var total_var = jStat.pooledvariance([group_a, group_b, group_c]); var total_lnvar = Math.log(total_var); } else if (treatments == 3) { var total_var = jStat.pooledvariance([group_a, group_b, group_c, group_d]); var total_lnvar = Math.log(total_var); } else if (treatments == 4) { var total_var = jStat.pooledvariance([group_a, group_b, group_c, group_d, group_e]); var total_lnvar = Math.log(total_var); } //calculate test statistic var b_numerator = total_df * total_lnvar - sum_lnvar_df_array; var b_denominator = 1 - (-1 / (3*treatments)) * (df1_array_sum - total_df1); var b = b_numerator / b_denominator; var p = 1 - jStat.chisquare.cdf(b, treatments); console.log(df1_array, lnvar_array, total_df, total_var, total_lnvar, total_df1); //output results document.getElementById('B').innerHTML = "Test Statistic B: " + b.toFixed(5); document.getElementById('p').innerHTML = "p-value: " + p.toFixed(5); }