1. Week 3 LSP 120 Joanna Deszcz

2.  2 Methods  Particularly if goal is to measure the least and greatest occurrence of some quantifiable variable  Absolute Quantities  Relative Quantities

3.  Measure of the absolute occurrence of the variable  A “sheer” number  Tells how many or how much  Examples ◦ Number of students enrolled at DePaul ◦ Number of people in this class ◦ Number of babies born this year

4.  An absolute quantity divided by some other quantity  Calculated value  Tells percent, rate, fraction or ratio  Examples: ◦ Ticket sales per person ◦ Percentage of population infected with HIV by country ◦ Percent increase in population by state

5.  Fraction or Percent ◦ Used when comparing part to total of the same type of variable ◦ Percent of people infected with HIV  Infected population/Total population ◦ Also used to show relative change  More to come…

6.  Ratio ◦ Used to compare the same type of variable from two sources ◦ Example:  California’s population is 33,872,000  Oregon’s population is 3,421,000  How many times larger is CA than OR?  Divide CA/OR = 9.90  CA is almost 10 times larger

7.  Rates ◦ Used to compare different types of variables ◦ Examples  Miles per hour  Tickets per person  Crimes per 1000 people

8.  Let’s work with some absolute and relative quantities  HIV_Adults_By_Country_2001.xls HIV_Adults_By_Country_2001.xls  StateLotteries.xls StateLotteries.xls

9.  Describes the actual increase or decrease from a reference (or old/earlier) value to a new (or later) value  Formula ◦ Absolute Change = new value – reference value

10.  Compares the absolute change to the reference value  Formula ◦ Relative Change = Absolute Change Reference Value or = new value - reference value reference value ◦ Convert relative change from fraction to % (with 2 decimal places) for readability purposes

11.  Absolute and Relative Change Absolute and Relative Change

12.  Already discussed ◦ Percent Change  Formula = (new-old)/old ◦ Percentage of  Main Formula is part/whole=% ◦ Absolute Change  Formula = new value – reference(old) value ◦ Relative Change  Formula = Absolute Change/Reference Value

13.  Percent More Than or “Times More Than” ◦ Example: The life expectancy in Canada is 79.1 years; the life expectancy in the US is 76.0 years. ◦ By how many percent is the life expectancy in Canada higher than the life expectancy in the US?  Answer - find percent change  (79.1-76.0)/76.0 = 0.041 or 4.1% ◦ How many times as large is the life expectancy in Canada than the life expectancy in the US?  Answer – divide Canada LE/US LE  79.1/76.0 = 1.041 times larger

14.  Percent Less Than  Same Example: The life expectancy in Canada is 79.1 years; the life expectancy in the US is 76.0 years. ◦ By how many percent is the life expectancy of people in the US lower than the life expectancy in Canada?  Answer – find percent change but divide by Canadian LE  (76.0-79.1)/79.1 = -0.039 or -3.9%