Biology 2244A/B Chapter Notes - Chapter 7: Confounding

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amethystcrow24

16 Sep 2016

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Observational study observing individuals and measuring variables of interested without attempting to influence the responses. Describe and compare existing groups or situations. Poor way to gauge the effect of an intervention. Experiment deliberately imposing some treatment on individuals in order to observe their responses. Purpose is to study whether the treatment (specific experimental condition applied to the subjects in an experiment) causes change in response. When the goal is to understand cause and effect. Two variables (explanatory variables and lurking variables) are confounded when their effects on a response cannot be distinguished from each other. Population: the entire group of individuals (not necessarily people) about which we want information. Sample: the part of the population from which we actually collect information (we use the sample to draw conclusions about the entire population) Sampling design: describes how to choose a sample from the population.

Related Questions

You believe that playing rap music has a positive effect on plant growth and color. You want to convince others of it too, so you set up an experiment. You have 8 raised beds and in each raised bed you put 20 tomato plants. You have one big isolated sound barrier and put 4 beds on each side of it and play the music on only one side of the wall.

3a What would be your null-hypothesis?

3b What would be your alternative hypothesis?

3c How many replicas are there?

3d How many treatments are there?

3e What is the treatment group?

3f What do you call the group that does not get the treatment?

3g Name 3 possible confounding factors that might influence your research.

3h What is the independent variable?

periwinkleporpoise604

4 According to a commercial, drinking water that has been blessed by Bill Nye the Science Guy improves your test scores. You think this is complete nonsense and want to disprove it. So you set up an experiment.

4a Would this be an observational or an empirical study?

4b To test it, for a total of 10 weeks, you take one test every week. Alternating weeks, you will drink regular water (control) and blessed water (treatment). How many replicas will you have?

4c What would be your null-hypothesis?

4d What would be your alternative hypothesis?

4e Name 3 possible confounding factors.

4f What is your independent variable?

4g Wat is your dependent variable?

4hs You set your a-level as always at 0.05, and do a statistical analysis to see if there is a difference in test scores between the two groups. The statistical analysis result is p=0.06 Is there a significant difference in test scores? Yes / No / Donât know

4i Based on the statistical analysis outcomes, does drinking blessed water improve test results? Yes / No / Donât know

4j 10 points A placebo effect is an improvement in a personâs perceived health from taking a non-active ingredient, presumably because of the belief that they are receiving a treatment helps that person to feel better. Your mind is a powerful thing and certainly can influence your health in real ways, so a placebo effect would include real improvements that come from âmind over matterâ as well as simple changes in perception. How can you avoid the placebo effect in this study?

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Biology 2244A/B Chapter Notes - Chapter 7: Confounding

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