rulerThis story in today's Nature caught my eye this afternoon. At first glance, I thought, "Why would someone want to make the most precise measurement ever?"

And then I remembered why I teach you all about the importance of precision in measurement during labs. You're probably wondering, "No you don't...you never mention that during our labs." Well, think about this: when I say in class, 'Does the ruler measure that accurately? Is it that precise?', that's when I'm trying to show you the importance of precision in measurement.


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You can't make an instrument more precise than its smallest possible measurement. For example, if you're measuring the length of a set of pea pods in millimeters, the average length of that set can't be 43.95254 mm. The rulers we have don't measure out to the ten-thousandths place! Your measurement instrument does have an element of uncertainty though, and that uncertainty is usually equivalent to plus or minus one-half of the smallest increment of measurement that instrument has.


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So why harp on precision? Why worry about accuracy? Think of instances in which it would be of utmost importance for a measurement to be as precise as possible.

Posted by scienceguru on November 15, 2007
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Total comments on this page: 29

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Andrea Deschenes on whole page :

I think that precision should be dealt with the best it can be, but in many cases, such as labs and minor things I don’t think that a decimal to the hundredth and such will make such a difference.
However I would think that precision would be somewhat important when it comes to medicine and things such as anesthisiolgy. If someone is debating on the correct amount of anesthesia to give a patient to make it safe for the patient I would like to believe that they are using the most precise measurements avaibleable to them!

November 16, 2007 5:16 pm
Isha Banerjea on whole page :

Everywhere in our world people are using the most precise measurements available, for good reasons. How about in the production of cars, airplanes, military weapons, mass transit, and so on? All of these man-made mechanisms had to have had derived from careful planning and extensive testing for the end product to have been approved for shipment or use. Just as Max Wertheimer said, “the whole is greater than the some of its parts,” without accuracy and precision the whole could be fatal.

November 18, 2007 11:17 am
Kaston Murrell on whole page :

Precision is always important to some degree. What good would a meter stick be with only two ticks, one for 0 mm and the other for 1000. What good would a thermometer be if it only measured 0 Celsius and 100? However even for everyday tasks and Biology labs it’s ok to round a little. However, like Andrea said, one of the most important measurements to get as accurate as possible is anesthesia for patients, too much, they die, go into coma, etc. Too little and they wake up painfully in surgery. Another measurement that has to be fine tuned is satellite speed. If they go too slow they fall into lower orbits and eventually crash or burn up. Too fast and they spin out to higher orbits and eventually escape Earth’s gravity.

November 18, 2007 5:27 pm
Ty Vessels on whole page :

In the labs we preform in class the error in our precision is important but not as much as in professional fields of study. For instance a biochemist’s measuring instruments would have to be very precise. Any physician in the medical field administering any kind of medicine should use the most precise measurements possible. An overdose could cause serious damage to the patient were as an under dose would not create the desired effect that the physician had originally intended for.

November 19, 2007 10:32 am
Angie on whole page :

One should try to be as precise as possible, given that nothing can be exactly accurate, it is still important. For example a surgeon operating in the heart or brain or on something equally precious; one millimeter one way or the other can can be lethal.

November 19, 2007 8:41 pm
Stephen Geest on whole page :

Howdy stephen here with thoughts on precision and its importance to science. of course we all strive to have the utmost precision on every experiment but i think, i hate to use extremes on anything but, that its impossible to obtain the perfectly percise measurment on any given experiment. thus it can yield a good result, sometimes the expected result is not always a good thing. we learn from our mistakes and we learn to tweek our experiments from those mistakes. Its my chrismas wish to have perfect precision, but it just aint happening. it that is not neccessaily a bad thing infact is a good thing. thanks for reading. ALPHA DAUG OUT

November 19, 2007 10:16 pm
Kelsey Wise on whole page :

I think precision is a necessity in science, yet it pertains differently according to what situation it is in. For example, in a biology lab, sometimes our precision will mean getting the measurement as close to a particular mark on a beaker as possible, yet in other experiments, a titration may be needed. However, in the real world, alot of times it is more crucial to get EXACT amounts as precise as possible, because just 1/10000 off could mean destruction to whatever is being measured. However, in the big picture, we will never be able to get the EXACT amount. Even under the higest powered microscope, there is always a smaller unit where we could measure a bit more. So basically, the amount of precision, thought it’ll never be exact, will depend on the situation.

November 20, 2007 10:05 am
Marcos on whole page :

First of all I would like to second the point made by a poster on the original article: that it is necessary to differentiate between precision
and accuracy, unless of course the scientists define them differently than we do in school.

November 20, 2007 4:08 pm
Marcos on whole page :

Secondly, I would offer an example of the importance of maintaining accuracy during calculations, which could bear significant importance in an experiment situation. In calculus, we have studied Newton’s method of approximating zeros of a function. The method involves calculating multiple iterations of a given formula until one reaches a value that is within x decimal places of the actual root. What makes Newton’s method work (usually) is that you plug the value obtained in the previous iteration back into the formula during the next iteration. Rounding the obtained value after each iteration will at a minimum increase the number of iterations you must calculate, and, if the final answer is to be rounded, could ultimately skew the accuracy of your result.

November 20, 2007 4:10 pm
Aadil Sarfani on whole page :

Precision is very important because your results can be very unreliable, especially if the numbers you are dealing with are very close together. Averages of numbers shouldn’t be rounded to more decimal places than given, for example, you can’t average 4.2 and 4.3 and say it’s 4.25. This is because your measurement’s value wasn’t 4.20, it was just 4.2. Even though it doesn’t usually make your data unreliable by adding extra decimal places, it looks stupid to show the average amount of time for a reaction to occur to be 23.9538 seconds.

November 21, 2007 1:02 am
David Golynskiy on whole page :

I think that precision is important because it produces a real 100% answer. No estimates/maybe’s/if’s. A precise measurement has precise answer/solution/result.

A real world implication would be the olympics. Every activity that is timed shows minutes, seconds, and milliseconds. It is very important to have the most precise time measurement so that every millisecond can make a difference between who wins and who doesn’t

November 21, 2007 8:56 pm
The Ger Bear on paragraph 4:

Generally, situations in which something brand new is created or something is uncertain, very precise measurements will be needed. Whether it’s anesthesia for a new patient, amount of chemicals necessary for a new compound, or something similar, it’s very important to be very precise.

However, if something is routine, like the amount of liquid necessary to fulfill a general requirement for a lab, the measurement can be rounded because of the knowledge that it will be okay. I know that’s a bit general, but I suppose what it comes down to is the familiarity of the experiment.

November 22, 2007 2:09 pm
kaitlin on whole page :

Precision is always necessary despite the fact that we, as humans, overlook this concept quite often. The problem with measuring might be that in order to include a smaller increment of measurement, one would have to be able to see smaller details. As it is, some people have a hard time counting the centimeter lines on a ruler let alone if a ruler could be broken down into smaller parts. Maybe the type of precision that is necessary isn’t the most plausible way of measuring. There are always digital and electronic ways of measuring that allows measurements of the smallest units incapable of being seen by the naked eye.
Such precision would be necessary when combining drugs for medicinal purposes as well as almost any measurement in the medical field.
For ruler manufacturers, please don’t make them with any smaller increments. I admit that I am one of the ones who uses their fingernail to keep track of what centimeter they are on.

November 22, 2007 3:26 pm
Neil on whole page :

When I first read this I was thinking of Botox as an example. But when I thought about it a little more, I realized that although this is a good example of needing a very precise measurement, a much more important example is Chemotherapy. Without an extremely precise measurement of the toxin, it would be very deadly. Maybe being more precise could help fight other illnesses or diseases.

November 22, 2007 6:26 pm
sussana elkassih on whole page :

After performing labs in chemistry you will not hesitate to acknowledge the importance of precision and accuracy (note these two terms stand for two different views of measurement). I cannot tell you how many times I felt I messed up a whole experiment just by using the wrong measurement of a solution when calculating percent error. I even remember a movie my class watched when I was in pre-AP chemistry about a town which had some percentage of (I think) fluoride in the drinking water which was causing all the children’s teeth to turn into different shades of brown, like a mouth full of cavities, but their teeth and gums where healthy, that’s when the toothpaste company Crest came up with a toothpaste with a very specific percentage of fluoride that helped the children’s teeth turn back to a normal shade of white. I’m sorry I can’t recall all the specific details (I might be wrong about the toothpaste company), but hopefully those who took pre-AP chemistry as sophomores remember. As much as I hate to painstakingly measure an object to the greatest precision and accuracy, I know that the slightest revision will have dramatic results, although not in every situation.

November 23, 2007 9:54 pm
Stephen Geest on whole page :

well after reading all these comments i am still going to have to stick to what i first said and that is nearly impossible to obtain a perfect result, whether or not we know it we are human and we are going to make mistakes, but i guess it might be possible to get one or two perfect and accurate results but i also think we can’t rely 100% on all experiments to be perfect. like i said earlier it’s not a bad thing to mess up, thats how we learn.

November 24, 2007 10:01 am
Prashi on paragraph 4:

well being precise is only as important as the mission. If you want to go for a jog, and you want cover 3 miles, at least I don’t measure to the last Inch. If you run a little extra so what, you’ll just get better, and if you’re a little short, you were probably tired anyways.

But if Kennedy and you’ve promised the nation that before the end of the decade you’re going to put a man on the moon, and your scientists really don’t care all that much about precision, well then “Houston.. we’ve got a problem..”

November 24, 2007 11:27 am
Andrea Deschenes on whole page :

If we really think about it…is it even possible to obtain something at the most precision? Is it ever possible to invent a tool that can precisly measure something 100% of the time? How do you know that that is the MOST precise measurment? They might say it is but in 20 years from now or so there could be a new instrument that is more precise so to say, so how do we know that what we are calling precise to be precise at all? There is always room for error.

November 24, 2007 11:56 am
Kaston Murrell :

I agree with Andrea. We may in fact think that we have the most precise measurement, 100% certain, or the most precise possible as with the article. However, we may be wrong. We assume that we are always a little off and rightfully so. However, what happens when we think we have the most precise measurement possible and later something happens to the uncertainty? We could make better ways to measure things or find out that old methods aren’t as good as we thought. Everything is eligible for question including how uncertain our answers are. Being human, we wont get anything completely right. However, striving to do so will at least get us close.

November 25, 2007 1:28 pm
Kishan Patel on whole page :

Using precise measurments is very important. Measurements have to be taken with the highest amount of precision and accuracy, when dealing in situations in space travel, under water exploration, or even in the hospitals. On great example of a need of precise measurements is Apollo 13. When the space pod had to enter earth they only had a two degree room for error. The smallest mistake could mean death for the three astronauts in the space rocket. In underwater exploration the amount of oxygen needed has to be measured with accuracy, the tanks have to be light, but have to contain enough oxygen for the people inside the exploration vehicle.

November 24, 2007 1:42 pm

Precision is VERY important, especially in the case above. Being exact in calculations is very important. In many situations, you will have once chance to get something right. The astronauts in the Apollo 13 mission only had ONE try to get the spacecraft into position, they did not have 3-4 tries to reenter earth and use accuracy to enter again. Many space missons have resulted in the loss of a spacecraft due to the fact that calculations were not done properly or not precise enough, losing years of work and millions of dollars. Even satellites are lost due to imprecise measurements while they are being moved into position.

November 25, 2007 10:48 pm
Noma on paragraph 4:

So based on most of the comments it seems that people are saying it’s okay to round in settings like labs since we do not have intricate measurement instruments at the high school level, but precision is very important nonetheless. Perhaps an experiment didn’t go well because of being off by a hundredth of a milliliter of solution. Because of these nuances in precision multiple trials should always be done in a lab to ensure the results are consistent.

November 24, 2007 7:20 pm
Kaston Murrell on whole page :

One important thing about precision is that we will always be at least a little off. Error due to uncertainty will always be there. Someone could use a measure of volume of water to be a standard measurement for mass and be very close but due to the difficulty of purifying water be off a little bit. Like I said earlier, precision is good but not always necessary in a great degree. I just got back from visiting my grandfather in Oklahoma and we passed mile markers all the way there and back. If some of those markers are a few inches, feet, or even yards off its not the end of the world. But if the GPS system in your crashed car only tells emergency workers where you are to within 200 feet, and you’re in the woods or its raining heavily or dark there’s a problem.

November 24, 2007 7:31 pm
Joshua Geevarghese on whole page :

being precise is really important. we cant really answer the question what is precise? how do we get to be precise? also we don’t really know that the measurements the ruler is showing is accurate. how did even people come up with this
if we ever find first ruler then we can see if our ruler is precise.this question is like the count in numbers.we cannot find answer to the question what will be the last number?

November 24, 2007 11:17 pm
Sara Lacock on whole page :

I’m not an expert in situations where precision can mean someone lives or dies, but I find it amusing how much we strive for perfection. Hopefully this precise measurement will be put to good use, but I’m sure most people will continue on using their rulers. It is amazing and hard to comprehend the inifite amount of numbers that are necessary in measurment. Humans do not have the capacity to hold this information (though some people seem to be able to memorize pi). Hundreds of years ago, precise measurement would not really be necessary and probably impossible without the use of calculators and technology. But with the way everything is improving, there is always some new technique or invention (yet these are never perfect and so a new version will soon be created). Got a little off topic there…but I just wonder how long it will take before everything becomes so advanced that all humans no longer focus on satisfaction and needs, but on wants and perfection. We already have hundreds of stores that sell slightly different/improved versions of things we already posses. Will everything become frivolous and unnecessary?

November 25, 2007 7:36 pm
Destiny on paragraph 3:

I think the amount we need to use of precision and accuracy depend on the time and predicament in which we are using it. If a scientist is inventing some new intivirus, then duh….measurements would be extremely important. On the other hand, if a certain student (Westiny) is doing a measurement, in a certain teacher’s class (Mrs. Fergie’s)…the measurements accuracy to the tenth decimal would not really be that important.

November 25, 2007 8:29 pm
Bonnie on whole page :

Precision is something that, as scientists, we must strive for. Obviously, 100% precision is not exactly attainable where we are right now. However, as many have said, there are very important places where precision is vital for survival. In a lab where we are measuring how far we can jump, sure precision would be nice to have then (if we are over the 1.5 meter mark!), but if you are off by a couple of centimeters, it’s not a huge catastrophe. Worst case scenario- you have to move out of the doohickey tree. Yet, there are more serious results if precision is not considered in other real-life situations, such as medicine. Doctors have symbols to eradicate doubt as to what amount of medication they are ordering for their patient. Any mix up could be life- altering. Another, slightly less serious and more obvious result of the lack of precision is when you are using spray on hair remover- intended for your legs. If it should unfortunately rub off on a large section of your arm during application, you will have a large “bald” spot on your arm for the next several weeks and have to answer several series of questions about how you accidentally shaved your arm.

November 25, 2007 9:48 pm
Katie Brkovich on whole page :

Precison is one of the most key things to science especially when it is dealing with experiments. Precison keeps what is going to happen with a reaction actually occur with the certain amounts of an element that are precise to the exactness. As somebody previously mentioned, precison does need to come down to the excatness of a tenth or hundreth of a decimal. That small amount can make the difference of it happening or not. Precison is so essential to the nature of science and activities that are conducted.

November 25, 2007 10:04 pm
Bonnie on whole page :

Also, in reference to Sara’s comment before, it really is amazing how quickly and efficiently we are evolving. The precision with which we go about our daily functions would’ve never been achieved by our predecessors. Just look at the calculator, it’s a common thing to require every student to have one for basic, standard math. However, even just a few years ago when my dad was in high school (well, maybe more than just a few, but shh!) they were still largely unheard of. My grandfather (a retired bio-chemist professor) still has a slide rule proudly displayed on his desk, as if to say, “Yes! I accomplished all of these scientific achievements without lowering myself to using a brain other than my own!” In a span of 50 years, we’ve progressed to calculators that can solve horrendously long problems in a matter of milli-seconds, spitting out a precise answer that would’ve taken much longer years ago, probably not even coming close to the precision we are able to achieve today.

November 25, 2007 10:10 pm

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