# Internet Activities

### Chapter 7

Click on the following links - please note these will open in a new window

In Chapter Seven, the notion of a probability sample was introduced. Begin by reading more about probability sampling and types of probability samples at the Statistics Canada Web site: http://www.statcan.gc.ca/edu/power-pouvoir/ch13/5214895-eng.htm

Next, let's try a few sampling simulations. Navigate to the following URL: http://onlinestatbook.com/stat_sim/sampling_dist/index.html

Click the "Begin" button on the upper left of your screen. At this point, a new window will open for you. Maximize this window. The distribution at the of your screen is a population distribution. The idea here is that we are going to draw several samples from this population. In doing so, we will see not only what the distribution of our sample looks like, but also how the sampling distribution takes shape.

Under the "Sample:" label, click the "Animated" button. You have just drawn one sample of size five from the population. This sample is plotted in the second graph from the of your screen. What this simulation also did was to calculate the mean of this sample and plot this value in the third graph from the of your screen. Thus far, we have only drawn one sample. Therefore, repeat the process of drawing a sampling by clicking the "Animated" button until you have drawn 50 or more samples of size 5 from the population.

Once you have completed the task above, take a moment to examine the shape of the sampling distribution relative to the shape of the population distribution. On the left side of your screen, compare the mean values for the sampling distribution and the population distribution. Are they similar? Are they identical? Why or why not?

Having made it this far, notice that there are three additional buttons under the "Animated" button. These allow you to drawn 5, 1,000, or 10,000 samples at a time. But, first, you need to clear the results of the previous simulation. Do this by clicking the "Clear lower 3" button at the of your screen. You are now ready to drawn multiple samples at once. Click the "1,000" button. In doing so, you have drawn 1,000 samples of size 5. Again, clear your work, and then try clicking the "10,000." You should see a marked difference in the shape of the sampling distribution. Take a moment to summarize these differences.