Air pressure as a function of height, p. 2: residuals from the simple linear regression of pressure (in mmHg) on height. ------- [1,] [2,] [3,] [4,] [5,] [6,] 145.859857 136.110876 126.361895 116.512913 107.063932 97.514951 [7,] [8,] [9,] [10,] [11,] [12,] 88.265970 78.916988 69.668007 60.619026 51.670044 42.921063 [13,] [14,] [15,] [16,] [17,] [18,] 34.572082 26.123100 18.074119 10.325138 2.576157 -4.872825 [19,] [20,] [21,] [22,] [23,] [24,] -12.421806 -19.370787 -26.319769 -39.617731 -52.315694 -64.513657 [25,] [26,] [27,] [28,] [29,] [30,] -75.911619 -86.609582 -130.799395 -160.789208 -178.379021 -185.168834 [31,] [32,] [33,] [34,] [35,] [36,] -182.458647 -171.048460 -151.638273 -125.728086 -94.817899 -60.007713 [37,] [38,] [39,] [40,] 18.512661 104.833035 196.053409 290.233783 ----- These residuals show a very strong convex pattern, namely they start out positive and decreasing, become negative while still decreasing, reach a minimum at the 30th residual, then start to increase, eventually becoming positive and increasing. There is only one "turning point" where the residuals change between decreasing and increasing. This is very incompatible with i.i.d. residuals (normal or otherwise) so we'll consider other regressions.