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.
But September begins to feel like fall as days get shorter and cooler. Just like people, the trees in September begin to get ready for the coming winter. The trees which will spend the winter without their leaves, called deciduous trees, will soon begin turning color. It can be fun to do a study of which trees begin to change color first. Here are a few ideas to help you get started. Some trees which are not healthy change color before their neighbors.