Mathematics, 20.09.2020 16:01 greend0719

Select all designs which describe an observational study that is not a survey: 200 voters are randomly selected and asked how they will vote in an upcoming election.

60 pieces of lumber are randomly selected. Half of those are randomly assigned to be treated with a new dealer. 3 months later the level of rotting in the pieces is recorded.

* 100 pregnant women are randomly selected. For 8 weeks. the level of iron in their blood and their vital signs are recorded.

400 incoming 6th grade students are randomly selected. Researchers record their results on a reading test at the beginning and end of the school year and compare the level of improvement seen in students at elementary schools to students at middle schools.

300 people apply to test a new mattress. 100 of these customers are selected randomly to receive the new mattress and the others are given an older version. After 6 months they are asked to rate their satisfaction with the mattress.

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Select all designs which describe an observational study that is not a survey: *200 voters are rand...

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