numerical data
data which can be written in numerical form
mean
an average of n numbers computed by adding some function of the numbers and dividing by some function of n
median
relating to or situated in or extending toward the middle
mode
the most frequent value of a random variable
trimmed mean
the mean of the data values left after "trimming" a specified percentage of the smallest and largest data values from the data set
resistant
incapable of being affected.
quartile
A division of the total into four intervals, each one representing one-fourth of the total.
percentile
(statistics) any of the 99 numbered points that divide an ordered set of scores into 100 parts each of which contains one-hundredth of the total
fence
the barriers that stop (Q +/- 1.5 IQR)
outlier
an extreme deviation from the mean
Standard Deviation
the square root of the variance
Varience
sqaure all the numbers in the data set and get a total, then divide by the amount of numbers and minus the mean squared to give you your varience.
Range
the limits of the values a function can take
linear transformation
when you multiply, divide, add, or subtract a constant from each score in a distribution. Changes the mean and/or standard deviation
linear combination
Method of solving a system of equations where first you multiply then add to eliminate a variable.
Boxplot
displays the 5-number summary as a central box with whiskers that extend to the non-outlying data values
Comparative Boxplot
A diagram that includes more than one boxplot using the same scale; allows the reader to find similarities and differences between data sets.
degrees of freedom
The number of individual scores that can vary without changing the sample mean. Statistically written as 'N-1' where N represents the number of subjects.
density curve
a curve with area exactly 1 underneath it whose shape describes the overall pattern of a distribution.
z-score
in a normal distribution it tells you how far a number is above or below mean in terms of standard deviations.
chebyshev's rule
for any number k >_ 1, at least 100(1-1/k squared)% of the observations in any data set are within k standard deviations of the mean; the percentage value is typically conservative in that the actual percentages often considerably exceed the stated lower
normal curve
a symmetrical curve representing the normal distribution
empirical rule
The rules gives the approximate % of observations w/in 1 standard deviation (68%), 2 standard deviations (95%) and 3 standard deviations (99.7%) of the mean when the histogram is well approx. by a normal curve