Statistical Methods & Analysis
MATH9875
Statistic/Procedure
Quiz 1 Formulas
Formula/Function
“array” refers to the set of values in your sample or population
2k Rule
“k” is equal to the number that makes 2k just greater than the number
of observations
Class Interval
i = (maximum value – minimum value)/k
Relative Frequencies
=Class Total/Total Frequencies *100%
Conditional Relative
Frequencies
=Cell Value/Marginal Value for the Condition *100%
Arithmetic Mean
=average(array)
Median
=median(array)
Mode
=mode(array)
Weighted Mean
=sumproduct(array of values, array of weights)/sum(array of weights)
Coefficient of Skew
=skew(array)
Range
=Max(array) – Min(array)
Variance
=var.p(array) or =var.s(array)
Standard Deviation
=stdev.p(array) or =stdev.s (array)
Coefficient of Variation
=standard deviation/mean x 100%
Q1: i=0.25*n
Q3: i=0.75*n
Quartile Value
Where i is the position of the data value. If i is not an integer, round up.
If i is an integer, take the average of the data values in positions i and
i+1
i=(p/100)*n
Percentile Value
Where i is the position of the data value. If i is not an integer, round up.
If i is an integer, take the average of the data values in positions i and
i+1
Interquartile Range (IQR)
=Q3 – Q1
Upper Fence
=Q3 + 1.5IQR
Lower Fence
=Q1 -1.5IQR
Standardized Value
(z-score)
=(value - mean)/standard deviation