Introductory Statistics

Formula Review

2.3Measures of the Location of the Data

$i=( k 100 )( n+1 ) i=( k 100 )( n+1 )$

where i = the ranking or position of a data value,

k = the kth percentile,

n = total number of data.

Expression for finding the percentile of a data value: (100)

where x = the number of values counting from the bottom of the data list up to but not including the data value for which you want to find the percentile,

y = the number of data values equal to the data value for which you want to find the percentile,

n = total number of data

2.5Measures of the Center of the Data

$μ= ∑ fm ∑ f μ= ∑ fm ∑ f$ Where f = interval frequencies and m = interval midpoints.

2.7Measures of the Spread of the Data

$s x= ∑ fm2 n − x ¯ 2 s x= ∑ fm2 n − x ¯ 2$ where