evidence: There are good reasons for all the corrections that NOAA applies to the data. The gridding process undoubtably improves the usefulness of the data internally. Artificial mapping discontinuities are smoothed over and trends will be clearer. But the corrections and the gridding process are statistical in nature, they do nothing to improve the accuracy of the National Temperature Index. If a specific problem with a specific thermometer is encountered and fixed, accuracy is improved. If the cause is not known and the readings are "adjusted" or "infilled" using neighboring thermometers or a statistical algorithm, the resulting maps will look better, but they are no more accurate. [...] Figure 4 shows the actual measurements from the stations, these are not anomalies and the data are not gridded. The raw data shows CONUS is cooling by 0.3°C per century, while the corrected data shows CONUS is warming by 0.3°C degrees per century. These lines, like all the fitted lines in this post, are Excel least squares trend lines. The lines are merely to identify the most likely linear trend in the data, thus the R2 is irrelevant, we are not trying to demonstrate linearity. [...] Figure 5. This plots the difference (Final-Raw) between the two actual station temperature curves in Figure 4. As you can visually see, the difference between the final and raw curve trends, since 1890, is about 0.8°C, roughly the claimed warming of the world over that period.