Representing Data - Measures
Quartiles
Quartiles are the quarter values. They are Q1, Q2 and Q3. Q2 is the median
Q1 = n/4
Q2 = n/2
Q3 = 3n/4
In grouped data you use interpolation.
Youstill calculate in the same way as in representing data - location except the quartile position is different and all the other values come from this position
The Interquartile range is Q3 - Q1
Q2 = n/2
Q3 = 3n/4
In grouped data you use interpolation.
Youstill calculate in the same way as in representing data - location except the quartile position is different and all the other values come from this position
The Interquartile range is Q3 - Q1
Percentiles
Percentiles split the data into 100 sections
The xth percentile (Px) is the xn th term
100
The interperceptile range from x% to y% is Py - Px
The xth percentile (Px) is the xn th term
100
The interperceptile range from x% to y% is Py - Px
Variance and Standard Deviation
The standard deviation is the mean deviation of a number from the mean
Standard deviation is given the symbol σ
The variance is the standard deviation squared
Standard deviation is given the symbol σ
The variance is the standard deviation squared
The equation for standard deviation is:
Coding
Same as in location except subtraction or addition don't affect standard deviation
E.g.
y = 10x - 3
Coded standard deviation = 14.1
Standard deviation = 1.41
E.g.
y = 10x - 3
Coded standard deviation = 14.1
Standard deviation = 1.41