There are three kinds of lies: Lies, Damned Lies and Statistics

Popularized by Mark Twain

Twisting information to your advantage…

What are Statistics?

Why are statistics useful?

What’s so good about Statistics?Statistics give us a way to look at the big

picture and get a much more accurate way of understanding what is going on in the world than what we could get from individual observations.

Misleading Statistics in Advertising This toothpaste is recommended by nine

out of ten dentists!Is this true?

Misleading Statistics in Advertising Statistics are a good way to show facts in

an easy-to-understand format, such as a percentage.

This has proven extremely successful because we, as consumers, like to believe all statistics are completely true

Problems With StatisticsWhile statistics are extremely valuable, they are also notorious for being a means that people use to make false and misleading arguments.

There are some main ways to manipulate statistics

The toothpaste advertisement is an example of selection bias.

Selection Bias A good sample is representative. This

means that each sample (person) represents the attributes of a known number of population.

Bias often occurs when the survey sample does not accurately represent the population. The bias that results from an unrepresentative sample is called selection bias.

Ways of Selection Bias: Undercoverage A common type of sampling bias is to sample

too few observations from a segment of the population.

A commonly-cited example of undercoverage is the poll taken by the Literary Digest in 1936 that indicated that Landon would win an election against Roosevelt by a large margin when, in fact, Roosevelt won by a large margin. A common explanation is that poorer people were undercovered because they were less likely to have telephones and that this group was more likely to support Roosevelt.

Other Ways to Collect or use Misleading Statistic:We have already looked at selection bias.In groups of 5-6 Investigate all of the following

ways to mislead consumers. Give examples to help your explanations 1) Use biased questions in your survey2) Ask the wrong question3) Use misleading graphs4) Imply cause and effect when you only have

correlation (what is correlation?) “Friends” causation

http://www.youtube.com/watch?v=fzxO_51HK_c 5) Make your results more precise6) Make up a statistic

Crime in AlburquerqueCan we trust statistics from th government?

http://www.youtube.com/watch?v=MTbZoKEOkUg

Questions to Ask When Looking at Data and Graphs

Is the information presented correctly?Is the graph trying to influence you?Does the scale use a regular interval?What impression is the graph giving you?

What is Wrong with this Graph?You will be given five graphs to critically

analyze in groups Discuss and decide as a group whether

the graph is misleading . Give an explanation and reasons why or why not.

If the graphs is misleading how could you improve this graph?

Year 7R is better at Maths than 7W. You will be given the year 7 Maths unit 1

test resultsIn groups use this data to calculate

mean, median and mode in a biased way to prove 7R is better at Maths than 7W! How would you do this?

Use this data to manually draw (or use excel) a misleading graph that shows year 7R is better at Maths than 7W.