Percent Difference And Percent Error
Contents |
a percentage of one (or both) values Use Percentage Change when comparing an Old Value to a New Value Use Percentage Error when comparing an Approximate Value to an Exact Value Use Percentage Difference when both percent difference formula values mean the same kind of thing (one value is not obviously older
Percent Difference Chemistry
or better than the other). (Refer to those links for more details) How to Calculate Step 1: Subtract one value from percent difference definition the other Step 2: Then divide by ... what? Percentage Change: Divide by the Old Value Percentage Error: Divide by the Exact Value Percentage Difference: Divide by the Average of The Two Values Step 3:
Percent Difference Physics Lab
Is the answer negative? Percentage Change: a positive value is an increase, a negative value is a decrease. Percentage Error: ignore a minus sign (just leave it off), unless you want to know if the error is under or over the exact value Percentage Difference: ignore a minus sign, because neither value is more important, so being "above" or "below" does not make sense. Step 4: Convert this into a percent difference excel percentage (multiply by 100 and add a % sign) The Formulas (Note: the "|" symbols mean absolute value, so negatives become positive.) Percent Change = New Value - Old Value × 100% |Old Value| Example: There were 200 customers yesterday, and 240 today: 240 - 200 × 100% = (40/200) × 100% = 20% |200| A 20% increase. Percent Error = |Approximate Value - Exact Value| × 100% |Exact Value| Example: I thought 70 people would turn up to the concert, but in fact 80 did! |70 - 80| × 100% = (10/80) × 100% = 12.5% |80| I was in error by 12.5% (Without using the absolute value, the error is -12.5%, meaning I under-estimated the value) Percentage Difference = | First Value - Second Value | × 100% (First Value + Second Value)/2 Example: "Best Shoes" gets 200 customers, and "Cheap Shoes" gets 240 customers: | 240 - 200 | × 100% = |40/220| × 100% = 18.18...% (200+240)/2 Percentage Difference Percentage Error Percentage Change Percentage Index Search :: Index :: About :: Contact :: Contribute :: Cite This Page :: Privacy Copyright © 2014 MathsIsFun.com
difference between the experimental percent discrepancy value and the theoretical value as a percentage of the theoretical value. In the http://www.mathsisfun.com/data/percentage-difference-vs-error.html definition below, "theoretical" is the value that is determined from theory (i.e., calculated from physics equations) or taken as a known or accepted value like g. ( 1 ) http://webassign.net/question_assets/ncsucalcphysmechl3/percent_error/manual.html % error = |theoretical − experimental|theoretical × 100% Percent Difference When wanting to compare two values that are both determined by experimentation, we don't have a "correct" or accepted value to which to compare, so we simply look at how different the two values are as a percentage of their average value: ( 2 ) % difference = |value 1 − value 2|value 1 + value 22 × 100%. Copyright © 2013 Advanced Instructional Systems, Inc. and North Carolina State University | Credits
"sizes" of the things being compared. The comparison is expressed as a ratio and is a unitless number. By multiplying these ratios by 100 https://en.wikipedia.org/wiki/Relative_change_and_difference they can be expressed as percentages so the terms percentage change, percent(age) difference, or relative percentage difference are also commonly used. The distinction between "change" and "difference" depends on whether or not one of the quantities being compared is considered a standard or reference or starting value. When this occurs, the term relative change (with respect to the percent difference reference value) is used and otherwise the term relative difference is preferred. Relative difference is often used as a quantitative indicator of quality assurance and quality control for repeated measurements where the outcomes are expected to be the same. A special case of percent change (relative change expressed as a percentage) called percent error occurs in measuring situations percent difference and where the reference value is the accepted or actual value (perhaps theoretically determined) and the value being compared to it is experimentally determined (by measurement). Contents 1 Definitions 2 Formulae 3 Percent error 4 Percentage change 4.1 Example of percentages of percentages 5 Other change units 6 Examples 6.1 Comparisons 7 See also 8 Notes 9 References 10 External links Definitions[edit] Given two numerical quantities, x and y, their difference, Δ = x - y, can be called their actual difference. When y is a reference value (a theoretical/actual/correct/accepted/optimal/starting, etc. value; the value that x is being compared to) then Δ is called their actual change. When there is no reference value, the sign of Δ has little meaning in the comparison of the two values since it doesn't matter which of the two values is written first, so one often works with |Δ| = |x - y|, the absolute difference instead of Δ, in these situations. Even when there is a reference value, if it doesn't matter whether the compared