Mean
the average of all the individual data values. To find the mean, add all the values and divide by the total number of data values; given by the formula x bar = sum of data values/number of data values
Statistic
number that describes some characteristic of a sample
Parameter
a number that describes some characteristic of a population
Resistant
a measure is resistant if it isn’t sensitive to extreme values
Median
the midpoint of a distribution, the number such that about half of the observations are smaller and about half are larger; if the n of data values is odd, the median is the middle value in the ordered list, if the number of n data values is even, use the average of the two middle values in the ordered list
Range
the distance between the minimum value and the maximum value; Range = Maximum - Minimum
Standard Deviation
measures the typical distance of the values in a distribution from the mean; calculated by finding an average of the squared deviations and then taking the squared root
Variance
the average squared deviation
Quartiles
divide the ordered data set into four groups having roughly the same number of values
First Quartile (Q1)
the median of the data values that are to the left of the median in the ordered list
Third Quartile (Q3)
the median of the data values that are to the right of the median in the ordered list
Interquartile range (IQR)
the distance between the first and third quartile of a distribution; IQR = Q3 - Q1
Five-number summary
consists of the minimum, the first quartile (Q1), the median, the third quartile (Q3), and the maximum
Boxplot
a visual representation of the five-number summary