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Now consider a different sampling method: What if you were to close your eyes and point blindly at the page with a pencil 10 times, taking for your sample the 10 words that your pencil lands on. 12. Do you think this sampling method is likely to be biased? If so, in which direction? Explain. A sample is only useful to us if the data we collect on our sample is similar to the results we would find in the entire population. In this sense, we say the sample is representative of the population. 13. Suggest another technique for selecting 10 words from this population in order for the sample to be representative of the population with regard to word length and e-words. Taking a simple random sample Key idea: A simple random sample ensures that every sample of size n is equally likely to be the sample selected from the population. In particular, each observational unit has the same change of being selected as every other observational unit. The key to obtaining a representative sample is using some type of random mechanism to select the observational units from the population, rather than relying on convenience samples or any type of human judgment. Instead of having you choose ârandomâ words using your own judgment, we will now ask you to take a simple random sample of words and evaluate your results. The first step is to obtain a sampling frame - a complete list of every member of the population where each member of the population can be assigned a number. Below is a copy of the Gettysburg address that includes numbers in front of every word. For example, the 43rd word is nation. 14. Go to the Random Numbers generator at http://www.random.org Generate 10 Numbers in the range from 1 to 268. What should you do if you get a duplicate number generated? Enter the random numbers in the table below: Randomly generated ten ID values from 1-268 Using your randomly generated values, look up the corresponding word from the sampling frame. Fill in the data table below. June 27, 2014 MAA PREP workshop 51