Comment by etchalon

3 years ago

We're talking about 0.3 micron measurements because the input value for his numbers is the efficiency of the filters in removing 0.3 micron particles (99.5 vs 99.95).

The author claimed the difference between the purified air, as a percentage of total air volume, was small. He used percentages expressed as a decimal to make that difference look small (0.9005 vs 0.90005). But a clever observer would translate those numbers back into their percentages (90.05 vs 90.005), start applying some math (i.e. 100000 x 0.9005 vs 0.90005), see the 10x difference, understand how that 10x different is going to multiply over time in a chaotic system, check the data to see if that's true, and then throw away the author's point.

Multiplying .9005 and .90005 by 10000 does not actually cause a 10x difference to appear. No, really, try it!

If your goal is to play with numbers, you could raise them both to a large power. You would discover that the ratio between them increases exponentially, but this would pale in comparison to the fact that both results would exponentially approach zero much faster than the ratio would increase.

  • 10000 x .9005 is 9,005. 10000 x .90005 is 9,000.5.

    Meaning that the first filter left 5 particles vs the second filter leaving .5 particles.

    A 10x difference.

    The goal isn't to "play with numbers" but to understand why/if the relative effectiveness of a filter results in a substantive difference in air quality.

    The data shows it does.

    • Extraordinary claims require extraordinary evidence. The data shows a huge difference which cannot be explained by the difference between 5 particles and 0.5 particles.

      As noted in the article, the Wirecutter does not explain its methodology or give particularly complete data, and what explanations they do give about filtration make no sense.

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