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 More
Probability, or the mathematical chance that something might happen, is used in numerous day-to-day applications, including in weather forecasts. For example, a weather forecast that predicts a 75 percent chance of snow is using probability to communicate that people should be prepared to deal with snowy conditions.Full Answer >
The different ways in which probability is used in real life include making odds of winning a major lottery game, weather forecasting, having coin tosses in sports and the playing of board games. Permutations and combinations are important in games of chance, such as state lotteries. Statisticians use probability to figure out a player's chance at winning the jackpot.Full Answer >
Direct variation exists when a worker is paid based on the number of hours worked. Another example of a direct variation is a taxi fare that varies according to the distance traveled. Direct variation occurs with two variables when the ratio of their values always remains the same. For example, if the value of A is always twice as much as B, they vary directly.Full Answer >
An example of a negative correlation in practical terms is that as a chicken gets older, they tend to lay fewer eggs. This is a negative correlation because as the years of the chicken increase, the number of eggs decrease, meaning that the two numbers are moving opposite from each other.Full Answer >