Potential Sources Of Error
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Sources Of Error In A Chemistry Lab
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Source Of Error Definition
Reference Homework Help Next What are possible sources of error in an experiment? My experiment is on testing nutrients in solutions, using test tubes and hot water baths, i need two sources of error, thanks:) 3 following 5 answers 5 Report Abuse Are you sure you want to delete this answer? Yes No Sorry, something has gone wrong. Trending Now Lady Gaga Houston Texans Chelsea
Types Of Sources Of Error
Clinton Mustard gas 2016 Crossovers Auto Insurance Quotes John Mayer Bobby Wagner Buffalo Bills Dating Sites Answers Relevance Rating Newest Oldest Best Answer: Incomplete definition (may be systematic or random) - One reason that it is impossible to make exact measurements is that the measurement is not always clearly defined. For example, if two different people measure the length of the same rope, they would probably get different results because each person may stretch the rope with a different tension. The best way to minimize definition errors is to carefully consider and specify the conditions that could affect the measurement. Failure to account for a factor (usually systematic) - The most challenging part of designing an experiment is trying to control or account for all possible factors except the one independent variable that is being analyzed. For instance, you may inadvertently ignore air resistance when measuring free-fall acceleration, or you may fail to account for the effect of the Earth's magnetic field when measuring the field of a small magnet. The best way to account for these sources of error is to brainstorm with your peers about all the factors
the measurement devices (hard to read scales, etc.) - Usually caused by poorly or miscalibrated instruments. - There are sources of error in a biology lab usually ways to determine or estimate. - Cannot reduce by
Sources Of Error In Measurement
repeated measurements, but can account for in some way. 3. Indeterminate (Random) Errors
- Natural non human sources of error in a chemistry lab variations in measurements. - May be result of operator bias, variation in experimental conditions, or other factors not easily accounted for. - May be minimized by https://answers.yahoo.com/question/index?qid=20090707145338AAaUiOa 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 readings or trials result in values close to the same number. Accuracy - relatively low determinate error. http://www.ahsd.org/science/stroyan/hphys/stats/meas_uncert_1.htm - 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 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 wiof this type result in measured values that are consistently too high or consistently too low. Systematic errors may be of four kinds: 1. Instrumental. For example, a poorly calibrated instrument such as a thermometer that reads 102 oC when immersed in boiling water and http://www.physics.nmsu.edu/research/lab110g/html/ERRORS.html 2 oC when immersed in 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. 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 error of the surrounding will not affect the readings taken when it actually 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 sources of error 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 one measurement you may start early and stop late; on the next you may reverse these errors. These are random errors if both situations are equally likely. Repeated measurements produce a series of times that are all slightly different. They vary in random vary about an average value. If a systematic error is also included for example, your stop watch is not starting from zero, then your measurements will vary, not about the average value, but about a displaced value. Blunders A final source of error, called a blunder, is an outright mistake. A person may record a wrong value, misread a scale, forget a digit when reading a scale or recording a measurement, or make a similar blunder. These blunder should stick out like sore thumbs if we make multiple m
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