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  • As the story goes, the legendary marksman William Tell

    故事是這麼說的,傳說中的神射手威廉特爾

  • was forced into a cruel challenge by a corrupt lord.

    被貪腐的君王逼迫要參加一殘酷的挑戰。

  • William's son was to be executed

    威廉的兒子會被處決,

  • unless William could shoot an apple off his head.

    除非威廉可以射到在他頭上的蘋果。

  • William succeeded, but let's imagine two variations on the tale.

    威廉成功了,但讓我們來想像看看這故事的兩個不同可能。

  • In the first variation,

    第一種情形,

  • the lord hires a bandit to steal William's trusty crossbow,

    君王雇用一名強盜去偷威廉慣用信賴的弩,

  • so he is forced to borrow an inferior one from a peasant.

    因此他被迫從農夫那借一次等的弓。

  • However, the borrowed crossbow isn't adjusted perfectly,

    然而,借來的弩並沒有被很完美地調整,

  • and William finds that his practice shots

    且威廉發現他的試射

  • cluster in a tight spread beneath the bullseye.

    都集中在靶心下面。

  • Fortunately, he has time to correct for it before it's too late.

    幸運地,在一切太遲之前他有時間做修正。

  • Variation two:

    第二種情形:

  • William begins to doubt his skills in the long hours before the challenge

    威廉在挑戰前的漫長時間裡,開始質疑自己的技術

  • and his hand develops a tremor.

    且他的手開始顫抖。

  • His practice shots still cluster around the apple

    他的試射仍然聚集在蘋果周圍,

  • but in a random pattern.

    但是散佈的很隨機。

  • Occasionally, he hits the apple,

    偶然,他也能擊中蘋果,

  • but with the wobble, there is no guarantee of a bullseye.

    但隨著搖晃,並沒有辦法保證正中靶心。

  • He must settle his nervous hand

    他必須使他緊張的手平靜

  • and restore the certainty in his aim to save his son.

    為了拯救他的兒子,他必須找回他的命中率。

  • At the heart of these variations are two terms often used interchangeably:

    這些變化中的核心,是兩個很常被互相替換的單字:

  • accuracy and precision.

    精密度和準確度。

  • The distinction between the two

    這兩者間的區分

  • is actually critical for many scientific endeavours.

    實際上對許多科學努力至關重要。

  • Accuracy involves how close you come to the correct result.

    精度牽扯到你離正確的結果多近。

  • Your accuracy improves with tools that are calibrated correctly

    隨著工具被準確地調教,你的精度會提升

  • and that you're well-trained on.

    你有受到好好的訓練也會。

  • Precision, on the other hand,

    另一方面,準度

  • is how consistently you can get that result using the same method.

    是你用同一種方式得到的結果有多高的一致性

  • Your precision improves with more finely incremented tools that require less estimation.

    隨著更多更精緻的工具的增加,其講求更少的估計,你的準度隨之提升。

  • The story of the stolen crossbow was one of precision without accuracy.

    弩被偷的故事主要關乎準度,而非精度。

  • William got the same wrong result each time he fired.

    威廉在每次射擊後得到同樣的錯誤結果。

  • The variation with the shaky hand was one of accuracy without precision.

    而關於手搖晃的情形,則是關乎精度而非準度的。

  • William's bolts clustered around the correct result,

    威廉的靶聚集在正確結果周圍,

  • but without certainty of a bullseye for any given shot.

    但在每一次的射擊中,缺乏正中準心的把握。

  • You can probably get away with low accuracy

    對於日常生活,低精度

  • or low precision in everyday tasks.

    與低準度是不會有太大影響

  • But engineers and researchers often require accuracy

    但是工程師和研究人員時常要求有微觀水平水準的準確性,

  • on microscopic levels with a high certainty of being right every time.

    必須有高度把握每次都正確。

  • Factories and labs increase precision

    工廠和實驗室透過更好的設備及更精細的製程

  • through better equipment and more detailed procedures.

    提升準度。

  • These improvements can be expensive, so managers must decide

    這樣的改進可能所費不貲,因此主管必須決定

  • what the acceptable uncertainty for each project is.

    每個專案中的不確定性能被接受的程度。

  • However, investments in precision

    然而,在準度上面投資

  • can take us beyond what was previously possible,

    可以帶我們超越先前的可能性,

  • even as far as Mars.

    甚至可以帶領我們到火星。

  • It may surprise you that NASA does not know exactly where

    可能會令你震驚的是,國際太空總署並不知道

  • their probes are going to touch down on another planet.

    他們的探測器在另一顆星球確實的著陸地點。

  • Predicting where they will land requires extensive calculations fed by measurements

    預測他們的著陸點需要使用測量結果做多方面的計算

  • that don't always have a precise answer.

    其不總是有準確的答案

  • How does the Martian atmosphere's density change at different elevations?

    火星的大氣密度如何在不同高度發生變化?

  • What angle will the probe hit the atmosphere at?

    探測器會以什麼角度進入大氣?

  • What will be the speed of the probe upon entry?

    探測器進入大氣前的速度會是多少?

  • Computer simulators run thousands of different landing scenarios,

    電腦模擬跑出上千種不同的著陸情境,

  • mixing and matching values for all of the variables.

    混和並配對這些值,以得到所有的可能性。

  • Weighing all the possibilities,

    衡量所有的可能性,

  • the computer spits out the potential area of impact in the form of a landing ellipse.

    電腦會以著陸橢圓的形式算出所有潛在的衝擊區域

  • In 1976, the landing ellipse for the Mars Viking Lander

    在1976年,維京一號火星登陸器的著陸橢圓

  • was 62 x 174 miles, nearly the area of New Jersey.

    尺寸為 62 x 174 英里,其大小接近紐澤西州。

  • With such a limitation,

    在這樣的限制下,

  • NASA had to ignore many interesting but risky landing areas.

    NASA 不得不忽視許多有趣但有風險的著陸區。

  • Since then, new information about the Martian atmosphere,

    從那時開始,關於火星大氣的新資訊

  • improved spacecraft technology,

    改進了太空科技,

  • and more powerful computer simulations have drastically reduced uncertainty.

    且更多強大的電腦模擬徹底地降低了不確定性。

  • In 2012, the landing ellipse for the Curiosity Lander

    在2012年,好奇號的著陸橢圓

  • was only 4 miles wide by 12 miles long,

    只有4英里寬,12英里長,

  • an area more than 200 times smaller than Viking's.

    此尺寸比維京1號的小超過200倍。

  • This allowed NASA to target a specific spot in Gale Crater,

    這讓NASA可以鎖定蓋爾撞擊坑上一特定的點,

  • a previously un-landable area of high scientific interest.

    這是先前無法登陸,但有高度科學重要性的區域。

  • While we ultimately strive for accuracy,

    當我們最終為了精度努力,

  • precision reflects our certainty of reliably achieving it.

    準度反映著我們有把握實現的確定性。

  • With these two principles in mind,

    只要在心中記住這兩個主要的原則,

  • we can shoot for the stars

    我們可以射中星星

  • and be confident of hitting them every time.

    並有信心每一次都可以擊中。

As the story goes, the legendary marksman William Tell

故事是這麼說的,傳說中的神射手威廉特爾

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B1 中級 中文 美國腔 TED-Ed 威廉 大氣 火星 探測器 維京

【TED-Ed】精準和精確之間有什麼區別?- Matt Anticole (【TED-Ed】What's the difference between accuracy and precision? - Matt Anticole)

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    稲葉白兎 發佈於 2021 年 01 月 14 日
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