Making a Three-Stone Hearth as Efficient as an Improved Cookstove

Re:Making a Three-Stone Hearth as Efficient as an Improved C... by dalke on Monday December 21, 2015 @01:11PM (#10772414)

I am unfortunately distracted by the large number of significant digits. House 1 burned 2.785kg @ 0.038150685 kg/min, which implies a precision of micrograms per minute,

Using decimal math, that works out to exactly 72.99999986894075427479218263 minutes. Realistically, it's 73 minutes. There are only 2 significant digits so the reported rate should be 0.038 kg/minutes.

Also, there's is a factor of 3 variation in wood/meal unit, compared to 25% improvement in switching stoves. Why aren't all of the houses using the efficient cooking technique of house 3? For that matter, how reproducible are the numbers for each house?

Finally, I see that house 2 had no gains, using about the same wood/meal unit with all three stoves. Does this mean that about 1/3rd of the users of the stove will see no gain to switching? Or does it mean that there isn't enough data to draw a good statistical conclusion? What are the odds of seeing these results purely from random chance?

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Re:Making a Three-Stone Hearth as Efficient as an Improved C... by twic on Monday December 21, 2015 @04:34PM (#10773688)

"Unfortunately, results from House 3 were often unreliable due to operational difficulties that caused large variations in meal size, type, and preparation."

I'd love to know the human story behind these "operational difficulties".

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Re:Making a Three-Stone Hearth as Efficient as an Improved C... by semi-extrinsic on Monday December 21, 2015 @03:57PM (#10773461)

From TFA:

"The operator and the conditions of use largely determine the effectiveness of operation."

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Re:Making a Three-Stone Hearth as Efficient as an Improved C... by dalke on Monday December 21, 2015 @04:26PM (#10773635)

I am unable to find that text in the article. I am even unable to find the word 'operator'.

In any case, I pointed out that there's a 3x difference between two houses, so I am in complete agreement with that statement. My post asks a different question, which is, what is the error range on the observed results? What are the odds that the stove doesn't actually have an effect on wood use, but that some other factor ('operator and the conditions of use') resulted in the observed differences?

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Re:Making a Three-Stone Hearth as Efficient as an Improved C... by semi-extrinsic on Monday December 21, 2015 @05:17PM (#10773952)

Ah, sorry, tab mixup on my end, the quote is from another article linked in the comments below; http://www.lowtechmagazine.com/2014/06/thermal-efficiency-co...

Anyway, the question you pose is a good one.

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Re:Making a Three-Stone Hearth as Efficient as an Improved C... by rasz_pl on Monday December 21, 2015 @09:48PM (#10775462)

Might be simple placebo effect, here have this super efficient stove.

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Re:Making a Three-Stone Hearth as Efficient as an Improved C... by dalke on Tuesday December 22, 2015 @02:01AM (#10776304)

I think you mean Hawthorne effect?

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Re:Making a Three-Stone Hearth as Efficient as an Improved C... by rasz_pl on Tuesday December 22, 2015 @02:17AM (#10776346)

I dont think so? They observed three families, but most likely told one of them all about the new amazingly efficient stove.

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Re:Making a Three-Stone Hearth as Efficient as an Improved C... by dalke on Tuesday December 22, 2015 @03:02AM (#10776463)

"The Hawthorne effect (also referred to as the observer effect) is a type of reactivity in which individuals modify or improve an aspect of their behavior in response to their awareness of being observed."

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