Some percent of understanding
Due Thursday at 10 p.m.
Learning questions: How can we use numbers to compare the quality of life of peoples around the world during the period 1-1500 CE?
Learning objectives: at the end of this lesson you should be able to-
- Accurately answer questions based on reading a spreadsheet.
- Calculate the relative percent change between two numbers.
- Calculate the absolute percent change between two numbers.
- Argue a thesis using per capita GDP and an article from our Normandale Library databases.
Background: What is a percent change?
You see the use of percents all the time in the news. Medical studies report "a 50% increased effectiveness," the state highway patrol may report "14% fewer traffic accidents," or a commercial may claim "50% whiter teeth." People use of percentages to convince us of the importance, accuracy, or effectiveness of their idea. And yet, without a basic knowledge of how to calculate percentages, we may be persuaded of the importance, effectiveness, or usefulness of an idea - contrary to our best interests. Most people recognize this challenge with percent changes, and conclude to either ignore or believe percent change claims when evaluating the credibility of evidence.
So too in history, a failure to understand percent change can influence a historian's analytic conclusions. Does a 10% increase in the per capita GDP dramatically improve a countries overall quality of living? As we'll see, it depends on what counts as "10%."
There are two main ways of thinking about percent: absolute percent change and relative percent change.
Let's work with examples: You have 100 sheep. One dies this year due to illness. So, you have a 1% mortality (death) rate. If next year with 100 sheep, 2 sheep die, you have a 2% mortality rate. If you want to know how much the mortality rate has gone up, you could subtract 2%-1%, and your absolute percent change is 1%. However, if you want to calculate the relative percent change you have to subtract 2%-1%, divide by the original % (1%) and then multiple by one hundred. 2%-1% = 1% divided by 1 is 1 times 100 = 100%. So, the relative percent change is that your mortality rate increased 100%. The equation is ((b-a)/a) x 100 for relative change.
The equations for change are
Absolute percent change: (b%-a%)
Relative percent change: (b-a)/a) x 100
Saying that the mortality rate increase by 1% or 100% are both accurate statement, but which number do you feel captures the importance to a farmer?
People use absolute percent change and relative percent changes all the time in history. For example, you could say the plague killed 40% of the populace in the middle of the 13th century (an absolute percent change) or you could say the mortality rate went up 400% (population in 1300 was 100 million, population in 1400 was 60 million).
Important: if you only have two numbers to begin with, you only calculate absolute change (b-a) and relative percent change (b-a)/a) x 100.
For this assignment you'll need to open the spread sheet on per capita GDP.
- What is the absolute change (b-a) of Japan's per capita GDP growth between 730 CE and 1450 CE?
- What is the relative percent change [(b-a)/a) x 100] of of Japan's per capita GDP growth between 730 CE and 1450 CE?
- What is the absolute change (b-a) of Iraq's per capita GDP growth between 730 CE and 1150 CE?
- What is the relative percent change [(b-a)/a) x 100] of of Iraq's per capita GDP growth between 730 CE and 1150 CE?
- What is the absolute change (b-a) of Egypt's per capita GDP growth between 730 CE and 1280 CE?
- What is the relative percent change [(b-a)/a) x 100] of of Egypt's per capita GDP growth between 730 CE and 1280 CE?
- What country had the greatest absolute change in per capita GDP during the period from 1 to 1500 CE?
- What country had the greatest relative percentage change in per capita GDP during the period from 1 and 1500?
- Using one of the Library Databases (Gale Virtual Reference Library, Daily Life in History, etc), explain why change occurred in Japan, Iraq, or Eqypt in a short paragraph (3-5 sentences)
- Find an article from a credible website (points only fro credible websites) about history before 1400 that uses a percent change and include the citation (URL or full citation) and whether you think the percent change is absolute or relative and why you draw this conclusion.
Post your answers to the Experiment 12 discussion board.
I expect this lesson plan to take approximately one hour.
- Accurately answered questions based on reading a spreadsheet.
- Calculated the relative percent change between two numbers.
- Calculated the absolute change between two numbers.
- Argued a thesis using per capita GDP and an article from our Normandale Library databases.
- Student selected a credible website for their percent change example.
- Student correctly identified the percent change as absolute or relative.