Main Sources Of Error
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the measurement devices (hard to read scales, etc.) - Usually caused by poorly or miscalibrated instruments. - There are usually ways to determine or estimate. - Cannot reduce by repeated measurements, but can account for in sources of error in experiments some way. 3. Indeterminate (Random) Errors
- Natural variations in measurements. - MaySources Of Error In A Chemistry Lab
be result of operator bias, variation in experimental conditions, or other factors not easily accounted for. - May be minimized by
Sources Of Error In Physics
repeated measurement and using an average value. Experimental results may be described in terms of precision and accuracy. Precision - relatively low indeterminate error.
- reproducibility. - high precision means a number of readingsSource Of Error Definition
or trials result in values close to the same number.
Accuracy - relatively low determinate error. - close to a true value. Accurate and precise Precise but not accurate Reliability- a procedure is said to be reliable if it may be completed with a high degree of accuracy and precision. For most of our investigations we will be concerned with the precision of results. Experimental Data and Measures of Uncertainty types of sources of error Quantities that give some measure of experimental precision are Deviation (individual values) Average deviation Average Deviation of the Mean (Standard Average Deviation) Sample standard deviation (sometimes denoted as ) Standard error It is customary to report experimental results with an uncertainty in the following form Result = Average ± uncertainty The uncertainty is one of the measures of precision given above (a.d., A.D., s, or Sx). For our present cases we will use standard error and report results as Result = Average ± Sx This information is simply preliminary to analyses we will be performing on some sample data, and data we will collect in the future. The idea here is to give you the formulae that are used to describe the precision of a set of data. We will see a bit more later. We need to see a calculation of these quantities. These pages illustrate one run through of calculations Another document will be about what these statistical quantities might tell us and how we might use this information to make certain decisions (usually as concerns elimination of data.) Reading Instruments and Errors Recorded values should reflect the precision of an instrument. Recorded values should have at least one more place than the smallest division on the scale of the instrument. Reaof this type result in measured values that are consistently too high or consistently too low. Systematic errors may be of four kinds: sources of error in measurement 1. Instrumental. For example, a poorly calibrated instrument such as a sources of error in a biology lab thermometer that reads 102 oC when immersed in boiling water and 2 oC when immersed in source of error definition biology ice water at atmospheric pressure. Such a thermometer would result in measured values that are consistently too high. 2. Observational. For example, parallax in reading a meter scale. http://www.ahsd.org/science/stroyan/hphys/stats/meas_uncert_1.htm 3. Environmental. For example, an electrical power ìbrown outî that causes measured currents to be consistently too low. 4. Theoretical. Due to simplification of the model system or approximations in the equations describing it. For example, if your theory says that the temperature of the surrounding will not affect the readings taken when it actually http://www.physics.nmsu.edu/research/lab110g/html/ERRORS.html does, then this factor will introduce a source of error. Random Errors Random errors are positive and negative fluctuations that cause about one-half of the measurements to be too high and one-half to be too low. Sources of random errors cannot always be identified. Possible sources of random errors are as follows: 1. Observational. For example, errors in judgment of an observer when reading the scale of a measuring device to the smallest division. 2. Environmental. For example, unpredictable fluctuations in line voltage, temperature, or mechanical vibrations of equipment. Random errors, unlike systematic errors, can often be quantified by statistical analysis, therefore, the effects of random errors on the quantity or physical law under investigation can often be determined. Example to distinguish between systematic and random errors is suppose that you use a stop watch to measure the time required for ten oscillations of a pendulum. One source of error will be your reaction time in starting and stopping the watch. During on
Celebrations Home & Garden Math Pets & Animals Science Sports & Active Lifestyle Technology Vehicles World View www.reference.com Science Chemistry Chem Lab Q: What are some possible sources of errors in the lab? A: Quick Answer Some possible sources of https://www.reference.com/science/possible-sources-errors-lab-5937a6475f2cd221 errors in the lab includes instrumental or observational errors. Environmental errors can also occur inside the lab. Continue Reading Keep Learning What are sources of error in a chemistry lab? What are some sources of error in synthesis of alum from aluminum foil? What is an example of a lab write up? Full Answer Instrumental errors can occur when the tools are not functioning exactly as they should be. An example of this error of error is a thermometer used to measure temperature. If the thermometer is not calibrated correctly, it can cause an error. An observational error example would be if the experimenter did not read the thermometer correctly when recording results. An example of an environmental error is when an air conditioner in a room causes the table to vibrate slightly and this vibration causes the measurement to be slightly off. Learn more about Chem Lab Sources: nmsu.edu sources of error columbia.edu Related Questions Q: How do you perform acid-base titration in a lab? A: Perform an acid-base titration in the lab by setting up a burette, dissolving the material for analysis in water in a flask, adding an indicator, recording... Full Answer > Filed Under: Chem Lab Q: What is an esterification lab? A: An esterification lab creates esters from the reaction between alcohols and carboxylic acids. Esters are commonly used as fragrances in things like perfume... Full Answer > Filed Under: Chem Lab Q: How do you learn common lab work abbreviations? A: Learn some common lab work abbreviations by studying a glossary of abbreviations, such as those available on NLM.NIH.gov, NewHealthGuide.org or Easy-Immune... Full Answer > Filed Under: Chem Lab Q: Where can you find used lab equipment for sale? A: Used lab equipment is available online through retailers such as Analytical Instruments and UsedLabEquipment.com, who test all equipment to manufacturer’s ... Full Answer > Filed Under: Chem Lab You May Also Like Q: What are some free sources for hilarious birthday cards? Q: What are some sources for viewing the Manitoba phone book? Q: What are some sources for free haircutting instructions? Q: What is the mass of aluminum foil? Q: What are some sources that sell muscadine grape juice? Q: What is the Erlenmeyer flask us