The 5,366 flight attendants in the study had higher incidence rates for every type of cancer examined, even though they had relatively lower rates of smoking and obesity. What type of observational study is this? A sample survey A study published in the journal Environmental Health found that flight attendants get cancer more often than the general population. Kara randomly selected members from their database, then contacted them to ask what kinds of equipment and services they would be most likely to use. The library where Kara works is planning to add a maker space where members can share equipment and services to create crafts.
Why might the rangers choose stratification instead of a simple random sample to estimate the proportion of infected trees? In repeated sampling, estimates from this sort of stratified sample would likely vary less than estimates from simple random samples.Ī stratified random sample reduces the likelihood of getting disproportionate numbers of cedar or oak trees in the sample. They'll sample trees from each side proportionately based on the total number of trees on each side. The rangers are considering taking a stratified random sample using each side of the creek as strata. West of the creek, most trees are cedar, which are more likely to be infected. East of the creek, most of the trees are oak. The population of trees in question is divided by a creek. *3000/20 = 150 Forest rangers at a national park want to take a sample of trees to estimate what proportion of trees in the park are infected with a certain disease. Which of these strategies will accomplish their intended design? Randomly select one of the first 20 guests to arrive and every 20th guest thereafter to take the survey. They want to take a systematic random sample of the 3000 guests they expect to attend. Managers of the venue want to survey approximately 150 guests at an upcoming concert about their overall experience.
Tickets in the orchestra zone are most expensive, and tickets in the balcony zone are least expensive. A concert venue offers tickets in 3 zones: orchestra, grand tier, and balcony.
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