What did we learn from the data? Does this sample convince you that more than half of all customers at this store are female? What do you think the real percentage is? 60%, 70%, 80%? What values are a reasonable guess for the population of females? What percentage was of females was present for our sample? Does our sample proportion convince you that more than half of all the customers at this Starbucks are female?
Roll 2 dice and add them together. What are the possible totals? Which sum will come up most often? Do these dice seem “fair”? How does this relate back to the sample data? Lets assume the Starbucks population is ”fair” or 50-50. Is there an experiment we can conduct to determine if your sample data is acceptable?
Flip your coin 26 times and record the results Can we extend this type of reasoning to our sample of 260 customers? Is it possible that 50% of the customers were male and 50% female and you just happened by coincidence to get more females in your sample? How can we decide whether our sample result is different enough from 50-50 to convince us there is something funny going on? Computer simulation
Let the computer applet toss a coin 260 times If we get heads, that customer is a female, tails means a male With this experiment, we can repeat the process of sampling from a 50-50 population many times (unlike the actual study)
Shaughnessy, M., Chance, B., and Kranendonk, H. (2009). Focus in high school mathematics: Reasoning and sense making in statistics and probability. NCTM. Key Curriculum Press: Exploring Statistics with Fathom, 2007 Coin Toss Applets: http://www.socr.ucla.edu/htmls/SOCR_Experime nts.html http://www.socr.ucla.edu/htmls/SOCR_Experime nts.html http://statweb.calpoly.edu/bchance/applets/Bino mDist3/BinomDist.html