CH.3 TERMS Flashcards
measures computed for data from a sample
Sample statistics
measures computed for data from a population
population parameter
a sample statistic of the corresponding population parameter
point estimator
average value for a variable
mean
value in the middle when the data items are arranged in ascending order
median
value that occurs with the greatest frequency
mode
how the data are spread over the interval from the smallest value to the largest value
percentile
specific percentiles
quartile
the difference between the largest and the smallest values
range
difference between the third quartile and the first quartile
interquartile range
average of the squared differences between each data value and the mean
variance
positive square root of the variance
standard deviation
measures the standard deviation relative to the mean
coefficient of variation
measures the shape of the distribution
skewness
standard value denotes the number of standard deviations of a data values xi is from the mean
z-score
if the distribution is roughly bell shaped then 68% is 1 SD of the mean, 95% is 2 SD of the mean, and 99.7% is 3 SD of the mean
empirical rule
observations with unusually large or small values
outlier
smallest value, first quartile, median, third quartile, and largest value are used to summarize data
five number summary
graphical summary of data based on five number summary
box plot
measure of the linear association between two variables, positive or negative
covariance
measures the relationship between two variables. Not affected by the units of measurement for x and y
correlation coefficient
mean is computed by giving each data value a weight that reflects its importance
weighted mean
