Backdoor Adjustment

Since version 10

// --------------------------------------------------------------------------------------------------------------------
// <copyright file="BackdoorAdjustmentExample.cs" company="Bayes Server">
//   Copyright (C) Bayes Server.  All rights reserved.
// </copyright>
// --------------------------------------------------------------------------------------------------------------------


using BayesServer.Causal;
using BayesServer.Causal.Identification;
using BayesServer.Causal.Inference;
using BayesServer.Inference;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace BayesServer.HelpSamples
{
    public static class BackdoorAdjustmentExample
    {
        public static void Main()
        {
            // This example uses Causal AI (Causal Inference)
            // to calculate P(Y | Do(X)) in the presence of
            // unobserved confounders, using the 
            // Backdoor Adjustment algorithm.

            var network = new Network();

            // TODO download the network from the Bayes Server User Interface (or Bayes Server Online)
            // and adjust the following path
            network.Load(@"Backdoor Collider.bayes");

            var x = network.Variables["X", true];
            var y = network.Variables["Y", true];
            var z = network.Variables["Z", true];
            var a = network.Variables["A", true];

            var inf = new BackdoorInference(network);
            var qopt = new BackdoorQueryOptions();
            var qout = new BackdoorQueryOutput();

            var query = new Table(y);
            inf.QueryDistributions.Add(query);

            // Set one or more interventions

            inf.Evidence.SetState(x.States[0], null, InterventionType.Do);

            // you could also set non-intervention evidence here

            // Method 1
            {
                // let the algorithm determine an appropriate adjustment set

                Debug.Assert(qopt.AdjustmentSetOverride == null);

                inf.Query(qopt, qout);

                Console.WriteLine("Method 1");
                Console.WriteLine(query[y.States[0]]);
            }

            Console.WriteLine();

            // Method 2
            {
                // supply your own adjustment set (e.g. using the BackdoorCriterion class)

                qopt.AdjustmentSetOverride = new AdjustmentSet(
                    new AdjustmentSetNode(z.Node),
                    new AdjustmentSetNode(a.Node));

                inf.Query(qopt, qout);

                Console.WriteLine("Method 2");
                Console.WriteLine(query[y.States[0]]);
            }
        }

    }
}