Popping the bubble, so to speak
Eternal optimist


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Drew Bell

I thiiiiiink they're trying to show the range of per-kilogram costs of polysilicon for the given years. So, in 2007, the price hit $200/kg at the market's lowest, and the high was $300/kg. When two thirds of your charts is forecast prices, though…

Luis Fernando

That's a very bad one. The only possible explanation is a high-low chart, like they use for stock analysis. Still, a bad one...

Bob Janes

Looks like no more than a graphic artist with imagination. The original - in the iSuppli report abstract at http://tinyurl.com/ckrmap - is just an Excel line chart with values for Spot Market prices.


Far too many gridlines, both horizontal and vertical, and the high-low prices coincidentally hit the round numbers too often. Coincidentally, or because they're really just guessing them?

If the gridlines weren't so numerous and thick black, the graph wouldn't have looked like a bad Mondriaan painting.


As Bob says, the original data were points that the artist has made inconsistently into ranges. If they wanted to express some uncertainty, a junkcharts-style makeover that I would recommend would be to replace the original points, without a line, and add error bars with a constant percentage range.

example here. Also, Business Week, notice how much more business-like it is?


Like Drew said, I think they are trying to depict the possible spread of polysilicon prices. You can see that in 2011 it is only half of the block or $100-50/KG. The graph is truly annoying.

Also isn't it somewhat deceptive saying the graph depicts 'Spot Prices' because a spot price is what you buy in the immediate future? Buying for the future is called a forward or future price.


Isn't it just a really bad version of a waterfall chart, apparently misused as well?


I'm not sure if the artist was even trying to convey any extra information not in the original chart.
I think he just thought it would be "neat" to make the chart sort of resemble a solar panel.
Of course, we are interpreting this as extra gridlines and an attempt to display some sort of uncertainty/range of values.

Not that I'm defending this chart in any way...


I hope that it displays the the range of polysilicon per-kilogram costs for the given years.


@Aziz, the forward price is the current price in the relevant futures market (i.e. you agree to complete the transaction in the future). The spot price is the price in the spot market (i.e. you agree to complete the transaction immediately). So a forecast of the spot price is trying to forecast what the price will be in the spot market in the future ... which may be different from the forward price in today's futures market!

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