Plot and interpret. As always, we first This line lies as close as possible to the examine the data. Figure 3 is a scatterplot points(in the sense of least squares)in of the crying data. Plot the explanatory the vertical (y) direction. The equation of variable(crying intensity at birth) the least-squares regression line is horizontally and the response variable(IQ at age 3)vertically. Look for the form, direction, and strength of the relationship y=a+bx=91.27+1493x as well as for outliers or other deviations There is a moderate positive linear Becauser=0.207, about 21% of the relationship, with no extreme outliers or n in IQ scores is explained by potentially influential observations intensity. See SPSS output Numerical summary. Because the scatterplot shows a roughly linear (Cormant GVING (straight-line)patte, the correlation describes the direction and strength of the relationship. The correlation between crying and IQ is r=0.455 Mathematical model. We are interested b Dopamin wabR in predicting the response from information about the explanatory variable. So we find the least-squares n line for predicting IQ from crying11 21 • Plot and interpret. As always, we first examine the data. Figure 3 is a scatterplot of the crying data. Plot the explanatory variable (crying intensity at birth) horizontally and the response variable (IQ at age 3) vertically. Look for the form, direction, and strength of the relationship as well as for outliers or other deviations. There is a moderate positive linear relationship, with no extreme outliers or potentially influential observations. 22 • Numerical summary. Because the scatterplot shows a roughly linear (straight-line) pattern, the correlation describes the direction and strength of the relationship. The correlation between crying and IQ is r = 0.455. • Mathematical model. We are interested in predicting the response from information about the explanatory variable. So we find the least-squares regression line for predicting IQ from crying. 12 23 This line lies as close as possible to the points (in the sense of least squares) in the vertical (y) direction. The equation of the least-squares regression line is Because = 0.207, about 21% of the variation in IQ scores is explained by crying intensity. See SPSS output: y ˆ =+ = + a bx x 91.27 1.493 2 r 24