Term
| voluntary response sample |
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Definition
consists of people who choose themselves by responding to a general appeal unreliable because they are biased since people with strong often negative opinions are most likely to respond |
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| entire group of indiv that we want information about |
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| part of the population that we actually examine in order to gather info |
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| systematically favors certain outcomes |
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Term
simple random sample (SRS) |
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Definition
basic probability sample
sample of size x consists of x indiv from the pop. chosen in such a way that every set of x indiv. has an equal chance to be the sample actually selected |
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1. each entry in the table is equally likely to be any of the 10 digits 2. the entries are independent of each other |
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population is divided into groups of similar indiv. (strata) a separate SRS is taken of each stratum; combined to form the full sample |
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| when some groups in the pop are left out of the process of choosing the sample |
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| when an indiv chosen for the sample can't be contacted or does not cooperate |
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| refers to the methos used to select the sample from the pop |
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choosing indiv who are easiest to reach
doesnt provide equal chance for members to be randomly selected |
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Definition
used to avoid the bias that can arise in a non-prob sample
-use some sort of random mechanism to choose the members of the sample |
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- respondent may not give transfer responses to a question -respondent may fail to understand the question -respondent desires to please the interviewer -ordering of the question may influence the response |
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Definition
| a sample that is selected from a pop in a way that ensures that every different possible sample of the desired size has the same chance of being selected |
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| the first member of the sample is chosen according to some random procedure and the rest are chosen according to some well-defined pattern |
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Definition
indivs on which the experiment is done
human beings: subjects |
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| specific experimental condition applied to the units |
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| explanatory variables in an experiment |
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| the response to a dummy pill that has no affect used as a control |
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| observational study vs. experiment |
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Definition
an observ study, responses arent influenced
an experiment actually imposes a treatment on the subjects in order to observe their resonses |
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| in an experiment studying the joint effects of several factors, each treatment is formed by a combining a specific value or level |
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| enables us to control the effects of outside variables on the outcome |
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| uses chance to assign subjects to the treatments; creates treatment groups that are similar |
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| statistically significant |
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Definition
| an observed effect so large that it would rarely occur by chance |
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Definition
| neither the subjects nor the people who have contact with them know which treatment a subject recieved |
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| random assignment of units to treatmesnt is carried out separately within each block (group of experimental units that are known before the experiment to be similar in some way that is expected to addeft the response to the treatments_ |
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| matches subjects in various ways they can produce more precise results than simple randomization |
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| completely randomized design |
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Definition
| when all experimental units are allocated at random among all treatments |
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| involved repeatings the exeriment on enough subjects to reduce the eggects of chance variation on the outcomes |
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Term
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Definition
the imitation of chance behavior, based on a model that accurately reflects the experiment under consideration
1. state the problem/describe experiment
2. state the assumptions
3.assign digits to represent outcomes
4.simulate many repetitions
5.state your conclusions |
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