何毓琦的个人博客分享 http://blog.sciencenet.cn/u/何毓琦 哈佛(1961-2001) 清华(2001-date)


On Research #9 - three things to remember 精选

已有 10513 次阅读 2007-10-19 18:14 |系统分类:海外观察

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On “How to do research” - #9

“Sanity checks in Research” ,  “欲速则不达”, and “Two wrongs

sometimes make one right”


There are many aspects of doing research successfully. Today, I

want to illustrate three aspects of this general problem using a real

incident which may be helpful to young researchers starting out.

First, when you “discover” a new results or formula, particularly if

it is after a series of long arguments or calculation, it is always a

good practice to do a “Sanity Check” on the result in order to

avoid making a silly mistake in the process of discovery or

derivation.  By sanity check I mean that you apply the result or

formula you derived to a known situation or an extreme situation

for which you already know the answer from independent

considerations.  If the result of application does not agree with the

independently known answer, then something is wrong. You need

to go back to check your derivation step-by-step.

Second, the pressure to get results in research often makes us

careless. The pressure to “publish”  also tends to rush us. But

research is basically built on painstakingly careful experiments

and analysis.  Sure we often have inspirations. But that is only the

beginning. The famous inventor Thomas Edison said it well

“success is 10% inspiration and 90% perspiration”.  The well

known Chinese saying “欲速则不达” cannot be more applicable here.

Lastly, “serendipity” does play a part in research. Lucky or

unlucky accidents happen. Sometimes two mistakes cancel each

other out, and you accidentally get the right answer. But pure luck

should not make you forget the first two dictates above. In this

case, it is even more important to carefully check the process of

getting to your results.

These three lessons of research combined to produce a comedy of

errors in my blog article of “Beijing sights and thoughts III –

energy cost of drying your clothes” dated Oct.19, 2007”

One of my Beijing experience during my recent trip to China was

the accidental observation of the Chinese and the US approach to

drying your laundry. http://sciencenet.cn/blog/user_content.aspx?id=9302 . I thought

this was an interesting observation on energy consumption and

environmental protection that have not been addressed before in

the public media. Thus, in the rush to get my blog article out, I

committed the second cardinal error above - “欲速则不达”. I did

not check my calculations carefully enough. The mistake was

detected quickly enough by a reader with the penname “confused”

(see comment associated with above blog article). So I quickly

admitted the error. But since the error did not materially change

the conclusion I was making, I did not bother to carefully check

the source data as the calculation mistake was plain enough.  Had

I done a “sanity check”,  I’d have discovered that my source data

was copied wrong. It takes 5 KWH of electricity to dry one load

of cloth not the 50KWH in the article. How should I have known

this? Here is my sanity check if I had done it. Yes, on the average

it takes one hour to dry one load of cloth (if you have lived in the

US, this is common knowledge). A simple hairdryer consumes

power at the rate 1KW. The heat produce by an electric dryer is

approximately that of five hair dryers NOT fifty hair dryers (again

this is common experience). Thus, I should have realized that the

figure 50KHW/load of cloth does not pass the sanity check. Since

I so readily agree with the reader “confused” about the calculation

mistake, I again should have realized that the figure  $750

billion/year of cloth  drying cost based  on the correct calculation is

unreasonable. The GNP of the US is only on the order of a few

trillions  dollars.  Finally this bring up my third lesson,  namely, the

conclusion of $75 billion dollars per year is not an  unreasonable

figure .  In my original article, I simply made two mistakes on

calculation and on source data that canceled each other out. The

final result does pass the sanity check.

In any case, here is my “mea culpa (我的錯)”. Let this be a lesson

to young researchers. One can never be too careful. Double

check and don’t rush!









不管怎样,这就是我自己犯过的一个错误。让它成为年轻科学家们的教训吧,要记住,在科研中,再细心也是不够的,一定要检查检查再检查,千万别着急!(何宏辉译 何姣校)



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