Statistics Flashcard

accuracy
a measure of how close a measured value is to the “true” value
determinate error
error due to procedural or instrumental factors that cause a measurement to be consistently too large or too small. the error can, in principle, be discovered and corrected (also called systematic error)
indeterminate error
a type of error, which can be either positive or negative and cannot be eliminated, based on the ultimate limitations on a physical measurement (also called random error)
precision
a measure of the reproducibility of a measurement
relative error
relative precision (rsd)
a measure of the precision of a measurement
significant figure
the number of significant digits in a quantity is the minimum number of digits needed to express the quantity in scientific notation. in experimental data, the first uncertain figure is the last significant figure.
degrees of freedom
in statistics, the number of independent observations upon which a result is based
confidence interval
the range of values within which there is a specified probability that the true value will be found
confidence level
Gaussian distribution
theoretical bell-shaped distribution of measurements when all error is random. the center of the curve is the mean and the width is characterized by the standard deviation. a normalized curve is also called the “normal curve”
mean
the average of a set of all results
median
for a set of data, that value above and below which there are equal numbers of data
range
the difference between the highest and lowest values in a set of data; also called “spread.” with respect to an analytical method, it is the concentration interval over which the linearity, accuracy, and precision are all acceptable.
standard deviation
a statistic measuring how closely data are clustered about the mean value.
pooled standard deviation
Q test
Grubbs test
statistical test used to decide whether to discard a datum that appears discrepant
t statistic
statistical test used to decide whether the results of two experiments are within experimental uncertainty of each other. the uncertainty must be specified to within a certain probability.
student’s t test
a statistical tool used to express confidence intervals to compare results from different experiments
variance
the square of standard deivation

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