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1. A Define Experiment Variables
An aspect of an experiment which changes during the course of the experiment.
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1.B Define Control (of an experiment)
The variable or part of the experiment to which all other can be compared.
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1. C Define Blind Studies
Experiments in which the participants do not know whether or not they are a part of the control group.
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1. D Define Double-blind Studies
Expertiments in which neither the participants nor the people analyzing the results know who is in the control group.
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1. When is an experimental variable good and when should it be reduced or eliminated?
An experimental variable is good when you are using it to learn something from the experiment. An experimental variable should be reduced or eliminated when it affects the results of the experiment but you do not learn anything from it.
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3. (story on pg. 79) What is the control for this experiment?
The control is the shirt that is being washed with no laundry detergent at all.
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4. What is the experimental variable that will be used to learn something from the experiment?
The type of detergent used.
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5. What are the experimental variables that need to be reduced or eliminated?
The washers are different. The water could be at different temperatures. The shirts are different. The amount of grass stain is different on each shirt.
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6. What could be done to reduce or eliminate the unwanted experiment variables?
The experimental variable of the washers can be reduced by making sure all washers are the same brand and model, and by making sure they are all relatively new. You can reduce the differences in water temp. by monitoring the temp. of the water as it enters each washer and making adjustments to keep the temp. the same. Shirts the same fabric, style, maker. Make stains identical as possible.
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7. Are the data collected objective or subjective?
The data being collected are subjective.
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8. Why can a carefully placed needle float on water, even though the needle is more dense than the water?
The needle floats because of surface tension.
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9. What does soap do to the surface of water?
Soap reduces the surface tension of water.
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10. A student tries to float a needle on water. He succeeds, but only after several attempts. He then tries to float the same needle on another liquid. Although the needle sinks when dropped in the liquid, it is much easier to lay the needle on the surface of this liquid and make it float than it was on the water. Compare the surface tension of this liquid to that of water.
The liquid must have a larger surface tension than the water, because the needle floats more easily on this liquid than on water.
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11. A new, fat free potato chip comes out on the market. A few months later, there are reports that some people get severe stomach cramps 1-4 hours after eating the chips. You must do an experiment to see if the chips cause severe stomach cramps. A group of people volunteer for the study. Describe how you would disign the experiment. Also, should it be blind, double-blind, or neither?
You should give half the volunteers the fat-free potato chips and the other half chips that have been on the market for years and have no problems associated with them. The volunteers then can keep a log (or you could observe them) for the next four hours to see of any stomach cramps occour. This should definately be a double-blind study.
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12.A study to see if a certain herb increase a student's concentration skills. A group of students volunteer for the experiment, which consists of giving the students a pill that is made up of either sugar or the herb. The students then take a series of math tests. The test scores of the students who take the herb will be compared to those who took the sugar pills. If there is a difference between the average test scores of the groups, it could very well be the result of the herb. Should this be a blind study, a double-blind study, or neither.
This should be a blind study.
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Number 13 in book
The study should be neither blind nor double blind.
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Number 14 in book.
This should be a double-blind study.
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