Spring 2010 Discussion Exercise 1 Name Matthew Marck Section 0101 1 Types of Variables It is important that you can identify different types of variables as Qualitative nominal or ordinal and Quantitative discrete or continuous Identify the variables being studied projects described below and give the type of variable for each qualitative nominal qualitative ordinal quantitative discrete quantitative continuous a A poll of registered voters in Michigan asking which candidate they support NOMINAL b The length of time required for a wound to heal when using a new medicine CONTINUOUS c The number of telephone calls arriving at a switchboard per five minute period DISCRETE d Whether students stayed up past midnight often sometimes rarely or never ORDINAL e The weights of people in a sample of elevator passengers CONTINUOUS f A movie critic s ratings of must see recommended not recommended or don t go ORDINAL g A movie critic s classification of drama comedy or adventure NOMINAL 2 Sampling Your TA will pass a container of beads around the room She will tell you what your sample number is whether you are the 1st 2nd etc person to sample Record this number Reach in and remove 10 beads ONE AT A TIME without looking Measure the maximum width of each bead to the nearest millimeter Calculate the average width of your 10 beads add the 10 widths together and divide the total by 10 Record your answer using 1 decimal place YOUR SAMPLE NUMBER 6 YOUR SAMPLE MEAN LENGTH 17 6 mm Open the Excel spreadsheet from Blackboard In order students will announce their sample mean You will enter this number in the column marked sample mean mm Excel will calculate the cumulative average bead length as the total sample size increases A line graph will be generated Copy the graph and insert it below a There should be a trend to your results Describe that trend below The trend seems to be that the graph is becoming more constant straighter b Why do you think this trend occurred I believe this trend is occurring because of more samples With more samples the variation of sizes gets smaller and smaller approaching one average size c What are the 4 aspects of a Good Sample as discussed in lecture 1 Random 2 Non Biased 3 Independent 4 Covers Entire Population d Which of the above aspects were violated by your sampling approach for these beads Explain why I would have to say that the selection of the beads wasn t quite random It was also not independent because once on person took their beads they left 10 less beads for the next person to choose from e Describe a different way to sample that would allow you to get a good sample of the average width of a bead Be sure to explain how this approach meets the 4 criteria above We could have numbered all of the beads and used a random number generator to create selections which we would correspond to the assigned beads This allows the entire population to be covered and randomly chosen not leaving a smaller population to choose from for the next surveyor Print assignment When printing choose to have 2 pages on a single sheet Hand in
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