Statistics

# Formula Review

StatisticsFormula 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 $z= (x-x ¯) s z= (x-x ¯) s$ and $z= (x-μ) θ . z= (x-μ) θ .$