dart_irt 0.0.1

A pure Dart library for Item Response Theory (IRT). Implements Rasch (1PL), 2PL, 3PL dichotomous models, polytomous RSM/PCM, EM/MML estimation, CAT helpers, DIF analysis, person estimators (EAP, MLE, [...]

example/main.dart

import '../dart_irt.dart';

void main() {
  // --- Rasch 1PL demo ---
  final rasch = RaschEM();

  final trueB = [-1.0, -0.3, 0.0, 0.4, 1.2];
  final rawX = IrtSim.raschResponses(
    persons: 400,
    b: trueB,
    missingRate: 0.05,
    seed: 7,
  );
  // Filter out persons with all 0 or all 1 responses
  final X = rawX.where((row) {
    final vals = row.where((v) => v != null).map((v) => v!.toInt()).toList();
    final hasZero = vals.contains(0);
    final hasOne = vals.contains(1);
    return hasZero && hasOne;
  }).toList();

  final res = rasch.fit(X);

  print('📊 Rasch: iter=${res.iterations}, LL=${res.loglik.toStringAsFixed(3)}');
  print('Estimated item b: ${res.b.map((e) => e.toStringAsFixed(2)).toList()}');
  print('First 5 theta(EAP): ${res.thetaEap.take(5).map((e)=>e.toStringAsFixed(2)).toList()}');

  // --- Basit 2PL kabuğu (şimdilik a=1.0) ---
  final irt2 = IrtDichoEM(model: DichoModel.twoPL);
  final dres = irt2.fit(X);
  print('\n📊 2PL (simple): a=${dres.a.map((e)=>e.toStringAsFixed(2)).toList()}');
  print('b=${dres.b.map((e)=>e.toStringAsFixed(2)).toList()}');

  // --- DIF (MH) örneği ---
  final group = List<int>.generate(X.length, (i) => i % 2);
  final rawScore = List<int>.generate(
    X.length,
    (i) => X[i]
        .where((v) => v != null && !(v is double && v.isNaN))
        .fold<int>(0, (a, v) => a + (v!.toInt())),
  );

  final dif = DifTools.mantelHaenszel(
    X: X,
    group: group,
    totalScore: rawScore,
    itemIndex: 2,
  );

  print('\n📊 DIF (MH) item 2: '
      'alpha=${dif.alphaMH.toStringAsFixed(3)}, '
      'delta=${dif.deltaMH.toStringAsFixed(3)}, '
      'chi2=${dif.chi2.toStringAsFixed(3)}, '
      'p=${dif.p.toStringAsExponential(2)}');
}