Business Stats

Data is described in 3 ways:

Tables: (freq distribution, Graphs (Bar charts, Histogram), Numerical Measures (Measures of central tendency; location, i.e perecntiles; dispersion)

Position of median

Mean of Sample Data

X bar

Mean of population Data

Meu

what do percentiles do?

Give the relative position/location of the element in the dataset

Percentile Location formula

i = percentile location, P = percentile

Element location for a percentile formula (when i isn’t an integer)

first element, found using location from i, + (difference between 2nd element - first element)* (the decimal component of i)

Q1

25th percentile

Q3

75th percentile

IQR

Q3-Q1

Upper Limit of boxplot

Q3+1.5*IQR

Lower limit of boxplot

Q1- 1.5*IQR

Any data beyond the limits are:

Outliers

Measures of Dispersion + Ex of them

Tell us the spread of the data (do data values remain consistent or do they change a lot) Ex: STD DEV

If range is low:

Values are relatively close and there’s less fluctuation in data

STD Dev (def + formula)

Tells us how far away from the mean data values are + square root of variance

STD Dev of sample formila

sqr root of:

STD Dev of population formula

Sqr Root of:

The higher the std dev:

further away values are from the mean