a summer in numbers, part II

Some further analysis. I copied the numbers into a stats program and did a linear regression analysis to see what relationship there was between the price per tree on any given day and how many trees I planted that day.

I didn’t include data from Lloyds, and created a weighted average tree price for days that we worked on two different cut blocks which had two different tree prices. I also cut out a couple of outliers (the last two days of the season that we spent climbing 30 degree slopes planting spruce with coke-can size pods into pieces deep enough that we couldn’t fit enough treees into our bags to make it to the back).

My hypothesis was that production would go down when tree prices went up, since tree prices are supposed to be dependant on how difficult the land is (and I think they were at ELF). Turns out the tree price didn’t affect my production very much. According to the linear regression model, only 8% of the variation in my daily production was due to tree price (R?=0.08).

I can think of two possible explanations.

  1. The obvious factor of land difficulty reducing production may be being counterbalanced by the fact that higher prices give more incentive to work hard and make money.
  2. I’m one of those lazy planters who sets a qouta and works towards it every day and slacks off once they get there regardless.

This raises the question of exactly what sort of distribution of daily totals I had. Were they clustered around some sort of daily qouta? Here’s the distribution:

I take three things from this.

  • The data aren’t exactly normally distributed, which I seem to recall breaks the assumptions of the linear regression modeal. I suspect that the dirty little secret of biological statistics is that this particular assumption gets broken in one out of every two papers published, so I’m going to let it stand here.
  • Maybe I do plant to a qouta. Something just below 2000 from the looks of it.
  • It looks like I’m settling into the charateristic planting signature of an older planter: very few (in fact, exactly 0) big exciting days, but a core of steady profitable ones.

Well, there you go.

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