Scientist and engineers compare a measurement to the accepted value using the term accuracy. The measurement system must provide both accuracy and precision if it is valid.
Accuracy relates closely to precision but is not the same. A common example includes the use of a target and darts. Four darts, with even spacing, around the bull's eye are accurate, yet not precise. Two darts with relatively close spacing yet far from the center of the target demonstrate precision but not accuracy. Accuracy and precision involve all darts landing near the bull's eye.
Scientists often express accuracy by means of significant figures. Convention dictates that the accuracy of the measurement is within one-half of the last significant figure. The accepted value results from repeated measurements of a traceable standard. The International System of Units defines these standards. In the United States, the National Institute of Standards and Technology maintains such traceable standards.
Increasing the number of measurements and averaging the results improves the accuracy of the measurement but does not necessarily improve the precision. In medicine and psychological studies, the scientist increases the number of measurements by increasing the number of participants in a study. However, increasing participants also increases the number of variables, some of which the researcher has not considered, into the study.
Learn MoreIn mathematics, the “average” typically refers to the “mean value” of a set of numbers that is found by adding all the numbers in the set and then dividing this answer by how many numbers were in the set. However, there also are other types of averages in mathematics, such as the weighted average, mode and median.
Full Answer >Cereal box size depends on the cereal brand and the volume size. For example, a box that is 12 inches long, 7 5/8 inches wide and 2 1/2 inches deep is required to hold 12.8 ounces of Multi Grain Cheerios.
Full Answer >The term "R-squared," or the coefficient of determination, explains the percent of variance away from a dependent variable and is expressed as a percentage between 0 and 100. An R-squared value explains how data fits a statistical set of numbers, sometimes expressed on a graph as a line or curve surrounded by points. The closer the R-squared value is to 100, the more dependent that value is on another variable.
Full Answer >The margin of error is calculated using two approaches: byÂ multiplying the critical value with the standard deviation of the statistic, or by multiplying the critical value with the standard error of the statistic when the standard deviation is unknown. In the field of statistics, the margin of error refers to the range of values contained in a confidence interval.
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