Statistics

Statistics

1. Descriptive

   • Summarizing the data, to get average of values
   • Central tendency
     • Mean
       • Affected by extreme values. why do we find the mean? mean of population is (mu)= Ex/N Mean of sample is (X-bar)= Ex/n
     • Mode
     • Median
       • arrange the data in accending order Extreme values doesn't affect the median
     • Percentile
       • percentile divides data in 100 parts. 6,9,11,11,11,14 1. Arrange in ascending order. 2. Q1= P(n)/ 100 (25*6)/100 Q1 (25%) = 1.5 NNOTE: if (i) is a whole number= the percentile is the avaerage of the (i)th and (i+1)th location. If (i) is not whole number= percentile os located at (i+1)th whole number
       • Quartile
         • quartile divides data into 4 parts
   • Variability
     • Range
       • highest number - lowest number
       • Interquartile range
         • Q3-Q1. Extreme numbers doesn't affect interquartile range.
     • Standard deviation

2. Inferential

   • Collecting sample from a population and finding the mean, mode and median of that sample, extrapolating the population.