What is Experimental error: Definition and 24 Discussions

Observational error (or measurement error) is the difference between a measured value of a quantity and its true value. In statistics, an error is not a "mistake". Variability is an inherent part of the results of measurements and of the measurement process.
Measurement errors can be divided into two components: random error and systematic error.Random errors are errors in measurement that lead to measurable values being inconsistent when repeated measurements of a constant attribute or quantity are taken. Systematic errors are errors that are not determined by chance but are introduced by an inaccuracy (involving either the observation or measurement process) inherent to the system. Systematic error may also refer to an error with a non-zero mean, the effect of which is not reduced when observations are averaged.

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  1. Lotto

    B How to statistically calculate the final value?

    My steps would be that I would first calculated ##a_1## and ##a_2##, determined by using that formula with partial derivatives its errors, and then I would made an arithmetic mean of ##a_1## and ##a_2##. I am not sure how to determine the final error, but I think I can use this formula ##\Delta...
  2. ohwilleke

    I Why Do Physicists Use Gaussian Error Distributions?

    David C. Bailey. "Not Normal: the uncertainties of scientific measurements." Royal Society Open 4(1) Science 160600 (2017). How bad are the tails? According to Bailey in an interview, "The chance of large differences does not fall off exponentially as you'd expect in a normal bell curve," and...
  3. I

    Bubbles in buret experimental error

    When bubbles are not removed from a buret before a titration, the measured volume of titrant used is more than the actual volume used. Then the analyte concentration will be greater than the actual concentration, and the mass of the analyte will be greater as well. Instead, it will actually...
  4. E

    Projectile Motion Experimental Error

    Homework Statement I got an experimental vertical acceleration of -12 m/s^2 of projectile motion for an experiment I did at home where I just had to throw a ball at around 45 degree to the horizontal up in the air and record it's motion, then analyze the motion via computer software. Obviously...
  5. MartinTheStudent

    I Do I use instrument error or arithmetic mean error?

    Hi. Let's say I have data which I have measured. For example I measured a length of an object and the measurment was repeated 5 times. An instrument which I used to measure has an error, value of which I know. My options are to either to just go with the instrument error (probably not, right?)...
  6. S

    I Why is the standard deviation the error on the singular meas

    I'm a beginner with the study in data analysis in Physics. I'm trying to understand the meaning, in the field of experimental Physics, of the standard deviation ##\sigma## of a series of data. There is one fundamental thing about ##\sigma## that I read but I could not understand. >In a series...
  7. RoboNerd

    Quick question on experimental errors

    Homework Statement A student is testing the kinematic equations for uniformly accelerated motion by measuring the time it takes for light-weight plastic balls to fall to the floor from a height of 3 m in the lab. The student predicts the time to fall using g as 9.80 m/s^2, but finds the...
  8. Alpha123

    Why the experimental error for CaOH is larger than MgO?

    Homework Statement I did a lab on the experimental application of Hess's law. There were two experiments where a substance in a solution was dissolved and the temperatures were recorded. Then the standard heat of formation for the substance was calculated. The first experiment used MgO and HCL...
  9. 24forChromium

    How to address experimental error in conclusion

    I am writing an essay which includes the experimental "verification" of a theory. As it turns out, the theory was able to predict a certain variable F's direction of change (i.e. increase or decrease across two data points) "correctly" for 90% of the time, and predicts the value of F at each...
  10. Ryaners

    Another Error Analysis Question - how to go about it?

    Hi folks, apologies if this is in the wrong forum. I'm a new undergrad physics student and I'm having trouble figuring out how to 'do' error analysis. (I had a quick look through some similar posts here & am still none the wiser.) I'll use my recent lab experiment on Resonance in a Tube as an...
  11. GiantSheeps

    Experimental Error in Archimedes Principle Lab

    Homework Statement I need to find three potential reasons for my .5% error in a lab where I used the Archimedes Principle to measure the density of Iron. We only used a graduated cylinder full of water and an iron mass. I measured the water level from the meniscus. We used two different...
  12. J

    Cp/Cv ratio experimental error

    Homework Statement Hello, Everyone! So I recently did an experiment in which I pressurised a vessel and then allowed some of the air to move into a smaller vessel and wait for the pressures to stabilise. I then calculated the Cp/Cv ratio and it was slightly lower than the expected 1.40. I am...
  13. L

    Calculating Experimental Error of Braggs Equation

    Homework Statement I am writing a lab report for an X-ray diffraction. I have been attempting to come up with an equation for the error using formulas some people from college gave me and also some I found on wikipedia but I am quite sure I am doing it wrong. The only variable is the angle...
  14. L

    Calculating Experimental Error

    Homework Statement I am writing a lab report for an X-ray diffraction. I have been attempting to come up with an equation for the error using formulas some people from college gave me and also some I found on wikipedia but I am quite sure I am doing it wrong. The only variable is the angle...
  15. C

    Calculating the strain in three different ways - experimental error?

    I've recently done an experiment where I've obtained the strain of a channel section beam in bending. I used a strain gauge to get the strain from the midspan and also used dial gauges to get the deflections of the beam under different loading conditions. Along with the readings I've...
  16. Darth Frodo

    G by free fall experimental error

    This isn't so much a H/W question, but we have 2 sets of values, TMax and Tmin. Δ is the difference between them. We are told to get Δ/2 and get the %uncertainty of this. Why do we halve Δ?
  17. A

    Understanding Experimental Error: Standard Deviation vs. Instrumental Precision

    When coming into contact with a result such as a + or - b, what should one take the quantity 'b' as? Is it always the standard deviation? Or is it an arbitrary uncertainty decided by the scientist running the experiment, based on the equipment? Please help. Thanks, Andrew
  18. R

    Projectile Motion Experimental Error

    Homework Statement We carried out an experiment where we launched a steel ball at different degrees. We then calculated the launch speeds for each launch angle. We got a percentage difference of 2.8% between the "most different" values. What are two qualitative reasons for this error...
  19. D

    Experimental Error on a quadratic

    Hello, I'm looking to derive the error of a quadratic equation as a function of x. y=ax2+bx+c y is measured and variables a,b,c have an associated error Da,Db,Dc To solve for x you complete the square. x=&\pm\sqrt{\dfrac{y-c}{a}+\dfrac{b^{2}}{4a^{2}}}\mp\dfrac{b}{2a} If the variables y,c...
  20. M

    Increasing the volume of solution lowers experimental error?

    Homework Statement This was part of a lab i preformed to determine rate law for HCl and Mg. 50 mL of 0.5M, 1M, 1.5M and 2M HCl solutions were made using water and this was used with Mg ribbon to find the rate law. The same 0.5M, 1M, 1.5M, 2M HCl solutions were made in 100mL solution that...
  21. G

    Understanding Experimental Error

    hi everyone ! when we say (for example)a,b and c are the dimension of Parallelogram a=2.267+- 0.002 cm b=3.376+-0.001 cm and c=0.207+-0.001 cm dose that means that we used equipment to calculat a and another to calculate b and c ? because i know that delta a or b or c is half...
  22. L

    Simple Experimental Error Problem

    I have two values: r = 12.3 ± 0.2m d = 0.57 ± 0.03mm I want to divide the two values to find theta (d/r = theta), how do I go about this? I assume that I add the experimental error margins together after the division of 12.3 and 0.57? Giving me: 4.63 x 10^-5 ± 2.0003m
  23. D

    Experimental error for the travelling microscope

    Whats the scale reading error for a traveling microscope Hi At school we done an experiment to determine the refractive index of a liquid using real and apparent depth. We used a traveling microscope a glass beaker and a coin. One question we got was what was the scale reading error...
  24. B

    Calculating % Error on Atwood's Machine Lab

    hi all im doing a lab on the atwoods machine basically i ahve calulated gravity as eqaul to 7.09 m/s^2 so i am way off because tis really 9.81. its because of human error when i was using the stop watch. i can't rember the formula for figuring out the perecentage of error even tho its really...