Formula Review

2.3 Measures of the Location of the Data

i=(k100)(n+1)i=(k100)(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(x + 0.5yn)(x + 0.5yn)(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.

2.5 Measures of the Center of the Data

μ=fmfμ=fmf where f = interval frequencies and m = interval midpoints.

2.7 Measures of the Spread of the Data

sx=fm2nx¯2sx=fm2nx¯2 where sx= sample standard deviationx¯ = sample meansx= sample standard deviationx¯ = sample meanz=x¯sz=x¯s and z=μθ.z=(x - mu)theta.