Crazy indicators

I was working in a rural area this week and stumbled upon this crazy market trend. The polynomial has a dramatic curve indicating a drastic change in the marketing adjustment. Over 3 years, the chart indicates an appreciating market at a rate of ~$176/day; however, the 1-year market trend indicates a depreciating market trend of ~ (-$197)/day. If I needed to use a very dated sale, I would need to apply a positive adjustment up to the change in the market and then make a negative adjustment for the more recent months. See your teacher was right, math is fun!