The Correlation. Correlation is a measue of how close the line fits the points that you found in your experiment. Anyone can say whether they think the line is a good fit or not, but to measure it exactly, we use the correlation coefficient: R2.
As the seasons change and the amount of sunlight decreases, less chlorophyll is produced, and the leaves appear less green. Chlorophyll is broken down into simpler compounds at a constant rate, so green leaf color will gradually fade as chlorophyll production slows or stops.
Some trees, notably elms, don't go through much color change at all; there's just a dull brown and then the leaf is gone with the wind. Weather: The temperature and moisture levels a tree is exposed to before and during the time its leaves' chlorophyll breaks down can affect color.