Stat Chapter 3

population parameter

a descriptive measure of a population. It is calculated using the population measurements

boxplot

a graphical potrayal of a data set that depicts both the central tendency and variability of the data. It is constructed using Q₁, Md, and Q₃

outlier

a measurement less then the lower limit or greater than the upper limit

coefficient of variation

a quantity that measures the variation of a population or sample relative to its mean

Chebychev's inequality (Theorem)

a theorem that (for any population) allows is to find an interval that contains a specified percentage of the individual measurements in the population

Empirical Rule

for a normally distributed population, this rule tells us the 68.26 percent, 95.44 percent, and 99.73 percent, respectively, if the population measurements are within one, two, and three standard deviations of the population mean

5 number summary

it consists of (1) the smallest measurement; (2) the first quartile; (3) the median; (4) the third quartile; (5) the largest measurement Sometimes a set of measurements are described by using...

range

the difference between the largest ad smallest measurements in a population or sample. It is a simple measure of variation

z-score

the number of standard deviations that a measurement is from the mean. This quantity indicates the relative location of a measurement within its distribution

percentile

the value such that a specified percentage of the measurements in a population or sample fall at or below it.

interquartile range

(denoted IQR) the difference between the third quartile and the first quartile (that is Q₃ - Q₁)

median

(denoted Md) a measure of central tendency that divides a population or sample into two roughly equal parts

mode

(denoted Mo) the measurement in a sample or a population that occurs most frequently

first quartile

(denoted Q₁) a value below which approximately 25 percent of the measurements lie; the 25th percentile

third quartile

(denoted Q₃) a value below which approximately 75 percent of the measurement lie; the 75th percentile

sample standard deviation

(denoted s) the positive square root of the sample variance. It is the point estimate of the population standard deviation

sample variance

(denoted s²) a measure of the variation of the sample measurements. It is the point estimate of the population variance

sample mean

(denoted x bar) the average of the measurements in a sample. It is the point estimate of the population

population mean

(denoted µ) the average of a population of measurements

population standard deviation

(denoted σ) the positive square root of the population variance. It is a measure of the variation of the population measurements

population variance

(denoted σ²) the average of the squared deviations of the individual population measurements from the population mean. It is a measure of the variation of the population measurements