Math

August 1

My goal this week is to finish the first chapter in Life of Fred: Statistics.

Notes so far:
Frequency distribution table.  It looks like an X and Y coordinate table, but has actual data on it.
Scatter Diagram.  Already knew that.  It looks like a scattered mess of dots.
Linear Regression.  At least the basics of finding the average and the sum.  And back to b=y-mx stuff.
Mean average: Added em up and divide by number of items.  Mean average of population is written in a Greek letter pronounced mew.  So, I guess cats are very good at figuring mean averages of populations.
Greek letters stand for things in the population and Roman letters stand for things in samples.  So, the really complicated swirly things are for the really complicated entire population.  The simple normal letters are for a sample of the population.
Histograms.
Mode Average: The most common reporting value.  Which is sneaky, because if two somebodies make $132,000 per year and all the 400 other somebodies make .27, .09, etc (all different amounts) then the Mode Average is 132K.  Which we know isn't the average salary of the whole city.
Variance: How much most of the things are away from the average.  You have to square all the differences to get rid of negative values, add em up and divide.
Standard deviation: You do some weird square root thingy with variance, which was squared in the first place, so that makes sense.
And the difference between standard deviation of a population (n things) and a sample (n-1).

In this chapter, Fred has contemplated buying a house, with the realtor offering true but misleading facts.  Caveat Emptor.  A salesman tried to sell him a travel package, also offering true but very general and misleading facts.  And poor Fred's math building and home have burned down.