Random Sample vs. Random Assignment
Now that our test if 45 mins and most likely some type of mutant FRQ, I think it's pretty much a lock that a good portion of it will be about research methods.
One of the easiest ways for the College Board to go is to make sure that you know the difference between these two terms.
Random Sampling is done when you are working on a survey. You can remember this because both the words sampling and survey start with an 'S'. In random sampling every member of the population you are studying has an equal chance of being selected. The best way to accomplish this is to create an alphabetical list of the population and select every Xth name depending on how big you need your sample to be. By randomly selecting participants you make an unbiased representation of the population. It does get a little more complicated than that. If you have small groups in your population that may be missed by a pure random sample you can do what is called representative sampling. (A representative sample is a subset of a population that seeks to accurately reflect the characteristics of the larger group. For example, a classroom of 30 students with 15 males and 15 females, could generate a representative sample that might include six students: three males and three females.)
Random Assignment is done when you are conducting an experiment. Remember that you can't force participants to take part in your experiment. The first need to volunteer but after they do, you need to put them into the control or the experimental group. You need to assign them randomly. To do this you again get an alphabetical list and then you assignment every other participant into either the control or experimental group.
What do both of them have in common? They both use randomness to keep biases out of the research. By randomly doing either you make sure that age, intelligence, gender, and personality do not become confounding variables.
One of the easiest ways for the College Board to go is to make sure that you know the difference between these two terms.
Random Sampling is done when you are working on a survey. You can remember this because both the words sampling and survey start with an 'S'. In random sampling every member of the population you are studying has an equal chance of being selected. The best way to accomplish this is to create an alphabetical list of the population and select every Xth name depending on how big you need your sample to be. By randomly selecting participants you make an unbiased representation of the population. It does get a little more complicated than that. If you have small groups in your population that may be missed by a pure random sample you can do what is called representative sampling. (A representative sample is a subset of a population that seeks to accurately reflect the characteristics of the larger group. For example, a classroom of 30 students with 15 males and 15 females, could generate a representative sample that might include six students: three males and three females.)
Random Assignment is done when you are conducting an experiment. Remember that you can't force participants to take part in your experiment. The first need to volunteer but after they do, you need to put them into the control or the experimental group. You need to assign them randomly. To do this you again get an alphabetical list and then you assignment every other participant into either the control or experimental group.
What do both of them have in common? They both use randomness to keep biases out of the research. By randomly doing either you make sure that age, intelligence, gender, and personality do not become confounding variables.
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