/**
 * ExperimentService - Epic 4: A/B Testing Infrastructure
 *
 * Implements:
 * - Experiment assignment system with balanced randomization
 * - Outcome tracking and data collection
 * - Basic statistical analysis
 * - Experiment lifecycle management
 */
import type { Database as DatabaseType } from '../db/database-interface.js';
import type { Experiment, ExperimentInput, ExperimentAssignment, ExperimentVariant, ExperimentOutcome, OutcomeInput, ExperimentAnalysis } from './types.js';
export declare class ExperimentService {
    private repo;
    constructor(db: DatabaseType);
    /**
     * Create a new experiment
     */
    createExperiment(input: ExperimentInput): Experiment;
    /**
     * Start an experiment
     */
    startExperiment(experimentId: string): boolean;
    /**
     * Pause an experiment
     */
    pauseExperiment(experimentId: string): boolean;
    /**
     * Complete an experiment
     */
    completeExperiment(experimentId: string): boolean;
    /**
     * Assign a user to an experiment (with balanced randomization)
     */
    assignUser(experimentId: string, userId: string): ExperimentAssignment;
    /**
     * Get user's variant for an experiment
     */
    getUserVariant(experimentId: string, userId: string): ExperimentVariant | null;
    /**
     * Record an experiment outcome
     */
    recordOutcome(input: OutcomeInput): ExperimentOutcome;
    /**
     * Analyze experiment results
     */
    analyzeExperiment(experimentId: string): ExperimentAnalysis;
    /**
     * Get all active experiments
     */
    getActiveExperiments(): Experiment[];
    private calculateStats;
    /**
     * Simplified t-test (for demonstration purposes)
     * In production, use a proper statistics library
     */
    private tTest;
    /**
     * Normal CDF approximation (Zelen & Severo 1964)
     */
    private normalCDF;
    /**
     * Calculate 95% confidence interval for difference in means
     */
    private calculateConfidenceInterval;
    /**
     * Make a recommendation based on statistical analysis
     */
    private makeRecommendation;
}
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