public void Should_Return_Correct_Pearson_Correlation_When_People_Have_Common_Preferences()
        {
            const string entity1 = "Lisa Rose";
            const string entity2 = "Gene Seymour";

            var entity1Preferences = new Dictionary <string, double>
            {
                { "Lady in the Water", 2.5 },
                { "Snakes on a Plane", 3.5 },
                { "Just My Luck", 3.0 },
                { "Superman Returns", 3.5 },
                { "You, Me and Dupree", 2.5 },
                { "The Night Listener", 3.0 }
            };
            var entity2Preferences = new Dictionary <string, double>
            {
                { "Lady in the Water", 3 },
                { "Snakes on a Plane", 3.5 },
                { "Just My Luck", 1.5 },
                { "Superman Returns", 5 },
                { "You, Me and Dupree", 3.5 },
                { "The Night Listener", 3.0 }
            };

            var preferences = new Dictionary <string, Dictionary <string, double> >
            {
                { entity1, entity1Preferences },
                { entity2, entity2Preferences }
            };
            var sim    = new Similarity <string, string>();
            var result = sim.GetPearsonCorrelation(preferences, entity1, entity2);

            Assert.AreEqual(Math.Round(result, 12), 0.396059017191);
        }