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Would taking measurements of the same object several times and then averaging them give a more accurate measurement?
Wiki User
∙ 12y ago
Generally, yes, because the averaging removes the effects of random errors in the measurements. However if your measurement technique has biases, these will not be removed through averaging and the averaged result will be biased.
Wiki User
∙ 12y ago
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Why are several trials taken for each measurement in an experiment?
A good way to reduce error or increase measurement accuracy is to take several measurements and compute their average. In other words, you achieve accuracy through averaging. (This also validates the repeatability of the measurement.)
How are precise and accurate measurements evaluated?
precision and accuracy are defined terms in science.Accuracy is the closeness of a given result to the true value of a measurement. Precision of a result is represented by the scatter of a number of measurements.True value is the average of a number of careful measurements by different experimenters, using different measuring systems. (consider the height of a mountain for example.)Resolution is merely the number of digits in the answer, and of which several may be meaningless.
How can you find error limit?
The error in a set of observations is usually expressed in terms of the Standard Deviation of the measurement set. This implies that for a given plotted point, you have several measurements.
How many mm is the thickness of a dime?
Cut to the chase and go to the link below if you are not interested in the empirical approach explained here. These are measurements that I took with my shiny 2005 dime and my Mitutoyo micrometer. The micrometer is in inches, and is several years old; it has gotten very little use and is in excellent condition. I converted my measurements in inches to mm. Presuming that my measurements are reasonably accurate, my dime is 1.19mm thick at the center, and 1.30mm thick at the edge. My measurement is a little different from the linked site information, which I can probably attribute to some wear on the coin, inherent limits of the micrometer, possible slight calibration error, or errors of technique. I re-measured, using 10 coins and 18 coins. Since I measure at the approximate center of the coins, and the stacks of coins rest edge to edge, I corrected for the top and bottom edges by adding to my average thickness the difference between my center and edge measures for one coin. For 18 dimes I calculate a thickness of 1.38mm For 10 dimes I calculate a thickness of 1.36mm All these measurements are telling me several things. My technique is reasonably good for "desk-top" work; my micrometer may not be as accurate or as well calibrated as I assumed; my correction factor for outer edges of stacked coins could be off and might be more accurate after several averaged measurements; there could be variability in the coins that I am not accounting for; the coins and the micrometer may not be at the correct temperature-- any number of other things may be affecting my measurements. One puzzling thing is that my measurement for the diameter of the dime is almost exactly in agreement with the link. I measure .7045 inches, and the site gives .705 inches. It's even possiblethat my measurement is closer to the actual measurement, and the site's .705 is a rounded figure. Nevertheless, this has been a lot of fun. See link for official specifications.
Which is more precise measurements a wooden ruler or plastic ruler?
Precision is the agreement among several trials in measurement therefor, a wooden ruler is more precise because you will be estimating the measured value over and over again
Why are several trials taken for each measurement in an experiment?
A good way to reduce error or increase measurement accuracy is to take several measurements and compute their average. In other words, you achieve accuracy through averaging. (This also validates the repeatability of the measurement.)
How do you know whether or not an observation is accurate?
You continue to make it repeatedly, with measurements of several kinds if possible, and you enlist the help of several others to make the same observation repeatedly and with measurements.
Can observation be accurate but not precise?
Accuracy, precision, repeatability and so on are terms that have been closely defined for measurement purpose. By folk such as ASTM. and ISO.The true value is the value towards which a large number of different measurements (by different measurement teams, using different measuring systems ... ..) tends.The accuracy of a particular method or measurement is how closely that answer comes to the True Value.The precision of a measurement represents the confidence you have in the measurement. (Generally by making several measurements.)The resolution of a measurement is merely the number of figures in your answer. A number with many places would have greater resolution, but many of those numbers might be meaningless.So, a single measurement of the height of a mountain for example, might be correct, (true value) but you don't necessarily have reason to be confident of the answer.
Why do voltmeters and ammeters have 2 or 3 scales?
When a meter has several scales, it also has a switch that allows you to select the most convenient scale for each individual measurement, so only one scale is used for one measurement. That gives you the ability to make the most accurate measurements over a wide range of voltage or current, almost as if you had two or three different meters.
How are precise and accurate measurements evaluated?
precision and accuracy are defined terms in science.Accuracy is the closeness of a given result to the true value of a measurement. Precision of a result is represented by the scatter of a number of measurements.True value is the average of a number of careful measurements by different experimenters, using different measuring systems. (consider the height of a mountain for example.)Resolution is merely the number of digits in the answer, and of which several may be meaningless.
Why do you use pH meter to measure the pH of several common household chemicals?
Using a pH-meter the measurement is more accurate and sure.
How can you find error limit?
The error in a set of observations is usually expressed in terms of the Standard Deviation of the measurement set. This implies that for a given plotted point, you have several measurements.
Is measuring the femur bone in an ultrasound an accurate way to give you an estimated time of conception?
The best person to ask is the person doing the ultrasound. Having said that here are a few guidelines. Ultrasounds can give you a fairly accurate time for the length of the pregnancy. Before 10 weeks the measurement taken is crown-rump length, from the top of the head to the bottom of the spine. This is accurate to within 3-4 days. After about 12 weeks several measurements are taken, head circumference, head diameter and abdominal diameter as well as femur length and the results are plotted on a graph to compare with the estimated length of pregnancy. The earlier the measurements are taken the more accurate they are in assessing the length of the pregnancy.
What kind of data do you put in arrays?
You should use arrays when you have several pieces of related data, of the same type. As an example, let's suppose you have a series of measurements, for example, temperature measured every few minutes. It doesn't make sense (from a programming point of view) to use a different variable for every measurement, so you store the measurements as a group - as an array.You should use arrays when you have several pieces of related data, of the same type. As an example, let's suppose you have a series of measurements, for example, temperature measured every few minutes. It doesn't make sense (from a programming point of view) to use a different variable for every measurement, so you store the measurements as a group - as an array.You should use arrays when you have several pieces of related data, of the same type. As an example, let's suppose you have a series of measurements, for example, temperature measured every few minutes. It doesn't make sense (from a programming point of view) to use a different variable for every measurement, so you store the measurements as a group - as an array.You should use arrays when you have several pieces of related data, of the same type. As an example, let's suppose you have a series of measurements, for example, temperature measured every few minutes. It doesn't make sense (from a programming point of view) to use a different variable for every measurement, so you store the measurements as a group - as an array.
Which is more accurate a plastic ruler or a steel ruler?
Accuracy has more to do with the measurement lines on the ruler than the material. In terms of making measurements , however, a steel ruler has several advantages to a plastic ruler of the same accuracy. For starters, steel rulers are often thinner than plastic rulers, positioning the measurement lines closer to the paper. As well as this, many steel rulers feature a backing made of a gripping material such as cork, which keeps the ruler firmly planted while drawing lines and making measurements. Lastly, the measurement lines on steel rulers are frequently embedded into the metal, whereas plastic rulers tend to have the lines painted on. After a while, these marks can be worn away, reducing the accuracy and readability of a plastic ruler.
How many mm is the thickness of a dime?
Cut to the chase and go to the link below if you are not interested in the empirical approach explained here. These are measurements that I took with my shiny 2005 dime and my Mitutoyo micrometer. The micrometer is in inches, and is several years old; it has gotten very little use and is in excellent condition. I converted my measurements in inches to mm. Presuming that my measurements are reasonably accurate, my dime is 1.19mm thick at the center, and 1.30mm thick at the edge. My measurement is a little different from the linked site information, which I can probably attribute to some wear on the coin, inherent limits of the micrometer, possible slight calibration error, or errors of technique. I re-measured, using 10 coins and 18 coins. Since I measure at the approximate center of the coins, and the stacks of coins rest edge to edge, I corrected for the top and bottom edges by adding to my average thickness the difference between my center and edge measures for one coin. For 18 dimes I calculate a thickness of 1.38mm For 10 dimes I calculate a thickness of 1.36mm All these measurements are telling me several things. My technique is reasonably good for "desk-top" work; my micrometer may not be as accurate or as well calibrated as I assumed; my correction factor for outer edges of stacked coins could be off and might be more accurate after several averaged measurements; there could be variability in the coins that I am not accounting for; the coins and the micrometer may not be at the correct temperature-- any number of other things may be affecting my measurements. One puzzling thing is that my measurement for the diameter of the dime is almost exactly in agreement with the link. I measure .7045 inches, and the site gives .705 inches. It's even possiblethat my measurement is closer to the actual measurement, and the site's .705 is a rounded figure. Nevertheless, this has been a lot of fun. See link for official specifications.
What is the realative mass and density of a nucleus?
This obviously varies according to which nucleus is considered, but the best modern measurements give the mass of a proton as 1.7x10-27kg. Similar measurements give the rms charge radius of around 0.9 femtometres. [For it is a probability measurement.] But there is a discrepancy of several standard deviations in this result, when compared to another measurement. [femto = 10-15 of a metre.] But for your purposes, you should be able to calculate the density.
