Why do I get 2, 5, 8, 11 in the Triangle column instead of 3, 6, 9, 12 when I use the ChainLadder package? df = pd.DataFrame({ 'origin': ['200101', '200105', '200203', '200204', '200310', '200311'], 'development': ['200103', '200207', '200206', '200301', '200312', '200405'], 'value': [100, 150, 200, 250, 300, 350] }) # Convert DataFrame to Triangle triangle = cl.Triangle(df, origin='origin', development='development', columns='value', cumulative=False) triangle_new = triangle.grain("OQDQ") triangle_new 2 5 8 11 14 17 20 23 26 29 32 35 38 41 2001Q1 100.00...