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- Multiple ChoicePlease save your changes before editing any questions.Runners after an ultramarathon commonly develop respiratory infections. We want to know if taking 600 milligrams of vitamin C daily will reduce these infections. Researchers randomly assigned 100 ultramarathon runners to receive either vitamin C or placebo. All subjects were watched for 14 days after the big race to see if infections developed. What are the possible lurking variables?Age of the runnerweight of the runnergender of the runnerall of the above
- Multiple ChoicePlease save your changes before editing any questions.Runners after an ultramarathon commonly develop respiratory infections. We want to know if taking 600 milligrams of vitamin C daily will reduce these infections. Researchers randomly assigned 100 ultramarathon runners to receive either vitamin C or placebo. All subjects were watched for 14 days after the big race to see if infections developed. The type of design used here?matched pairsrandomized blockcompletely randomizedstratified
- Multiple ChoicePlease save your changes before editing any questions.Can pleasant aromas help a student learn better? Two researchers believed that the presence of a floral scent could improve a person's learning ability in certain situations. They had 22 people work through a pencil-and-paper maze 6 times. Three of the times they wore a floral-scented mask and three times they wore an unscented mask. The three trials for each mask followed one another. Testers measures the length of time it took subjects to complete each of the six trials. They reported that, on average, subjects wearing the floral-scented mask completed the maze more quickly that those wearing the unscented mask, although, the difference was not statistically significant. This study is:a convenience samplean oberservational studyan experiment, but not double-blinda double-blind experiment
- Multiple ChoicePlease save your changes before editing any questions.The most important advantage of experiments over observational studies is thatA) experiments are usually easier to carry outB)Experiments can usually give better evidence of causationC) Confounding cannot happen in experimentsD) Observational studies cannot use random samples
- Multiple ChoicePlease save your changes before editing any questions.In order to perform an experiment using 60 members of a gym, I first divide the list of members into men and women because I feel that the results will be different based on gender. I then randomly choose 30 men and 30 women. I assign half of the men to the treatment group and half to the control group. I repeat this procedure with the women. This is an example of a:randomized comparative designblocking designmatched pairs designdouble blind simple random sample
- Multiple ChoicePlease save your changes before editing any questions.A market research company wishes to find out whether the population of students at a university prefers Starbucks or Dunkin Donuts. A random sample of students is selected, and each student is asked first to try both but the order they try them is randomly decided with a coin toss (heads: Starbucks, then Dunkin. tails: vice versa). They then indicate which brand they prefer. This is an example ofa completely randomized experimentan observational studya stratified samplea matched pairs experiment
- Multiple ChoicePlease save your changes before editing any questions.Why do we randomize in an experiment or a survey?Because we have toIt helps reduce the effects of confounding variablesIt eliminates all possible confounding variablesIt makes sampling easier
- Multiple ChoicePlease save your changes before editing any questions.
Identify the design for the experimentcompletely randomized, the factor is pesticiderandomized block, blocked on tree type, the factor is pesticideThis experiment is single blind, blocked by pesticideThe experiment is double blind, the factors are tree type and pesticide