Tuesday, December 4, 2012

88.2% of statistics are made up.

The British comedian, Vic Reeves, once quipped that "88.2% of statistics are made up." I thought of this when I saw the picture below:
Getting our students to be statistically literate must be one of our moral imperatives. This would partly involve developing our students' ability to ask the right questions in order to collect the right data so that they can display it in the clearest way. But we also need to help our students develop the ability to question any data that is presented to them, to see through the noise of misleading data and to reflect on such things as the sources of the data.
We gave the following question to a Grade 7/8 split class:
You are the CEO of a company that makes plastic water bottles. You need to create two graphs. One is to convince shareholders that you are making a profit. The other is to convince the Ministry of Environment that your company is environmentally responsible.
We purposely avoided giving them actual data to work with as we were more interested in how they would take into account that they have to present information to two very different audiences. Some used a single line graph and plotted time against the number of bottles sold:
Others created a double line graph, plotting their company's profit against another's over time:
For the second graph, some plotted the number of their bottles that were being recycled whilst others plotted the amount of 'pollution' over time, again compared to another company:
We then allowed students to go on a gallery walk and give feedback on other students' work.
They were reminded beforehand (as recommended by Dylan Wiliam) that the best sort of feedback is not ego-centred ('Great job') but task-centred and generally they were true to this. In the example below, students were asking how the author could possibly predict future sales. I like that!

In our consolidation we posed some further questions to the students:
1) Does it make more sense to have time measured in months or years?
2) Does it make more sense to have 'profit' or 'Number of bottles sold' on the y-axis?
3) How do you measure 'pollution'? Or how do you know how many of your bottles are recycled?
The ensuing conversation brought out a wealth of reasoning, proving and reflecting.
Afterwards, the teachers and principals who were observing remarked how this lesson could have easily have been a Media Literacy lesson.
Some recommended resources:
1) http://visual.ly/ has a huge amount of infographics that will be sure to kickstart some great data discussions.
2) http://nces.ed.gov/nceskids/createagraph/ I have never, since I started working in 1990, ever had to draw by hand a graph of any sort. All those hours spent converting data to percentages, then multiplying these by 3.6 to get degrees and then using these to draw (with a protractor) a pie chart were hours spent in vein. The Create-a-Graph site is very user-friendly and allows students to enter their data and choose the most appropriate way to display their data. After all, people in the real world will use technology to create graphs and charts, not be forced to draw them by hand.
3) Darrell Huff's How to Lie With Statistics although written in the 1950s is still wonderful reading. If you read it (I believe it can be downloaded for free now) you will become a better teacher, 100% guaranteed!

1 comment:

  1. Is that 100% guarantee at the end one of those "made up" statistics? Great post!