import numpy as np

class MonitoringEngine:
    def detect_drift(self, train_stats, new_data_stats, threshold=0.2):
        drift_flags = {}
        for feature in train_stats:
            if abs(train_stats[feature] - new_data_stats.get(feature, train_stats[feature])) > threshold:
                drift_flags[feature] = True
        return drift_flags