Unformatted text preview: ANS: This is a sample survey since a set of sampling units (sectors) is selected from the population of sectors to obtain information about that population. (c) In order to identify possible causes of tread separation on a particular model of SUV tire, quality engineers compare a sample of failed tires with a sample of unfailed tires with respect to a number of variables. ANS: This is a case-referent (or retrospective) observational study , since tires are grouped by end result (failure or not) and diﬀerences in hypothesized causes sought. 2. (5 points) Explain the best way to use blocking to improve the study described in 1(a). Be sure to tell how the blocking would help. ANS: Use each subject as a block and measure each under treatment (puzzle) and control (no stimulation). This would help reduce subject to subject variation....
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- Spring '08
- Magnetic resonance imaging, Crop yield