Statistics for Business: Decision Making and Analysis, 3rd Edition

... temperature average. On average, years with 25 ppm more CO₂ are warmer by about 0.25 degrees centigrade (about 1% of the change in CO₂). Should this relationship continue as observed, regression analysis predicts average annual temperature to be above the baseline by between 0.84 and 1.24 degrees if CO₂ levels reach 425 ppm.

Best Practices

• Verify that your model makes sense, both visually and substantively. If you cannot interpret the slope, then what’s the point of fitting a line? If the relationship between X and Y isn’t linear, there’s no sense in summarizing it with a line.

• Consider other possible explanatory variables. The single explanatory variable may not be the only important influence on the response. If you can think of several other ...