통계학 기초 개념 정리입니다.
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개념 정리와 예들.
A. Research design refers to the plan that we have for what we do with our sample and how we will make our measurements
The basic technique in research design is comparison. Through comparison we can answer questions that imply a contrast.
Example: Are depressed people more likely to commit suicide than nondepressed people?
The ways in which we make these comparisons differ:
1. We can compare individuals to themselves over time
2. We can compare one group to another group
3. We can contrast our sample statistic with our knowledge of the population parameter
4. We can contrast our sample with our knowledge of other samples that were studied at some other time or other populations
Research designs also vary in whether we attempt to manipulate what we are observing (these are called experiments) or we simply observe the phenomena (called observational studies)
Definition: An experiment is when a researcher imposes a treatment on elements in the sample (such as persons, animals, neighborhoods, etc.) and then observes or measures a response
Experiments can examine cause-effect relationships
In an ideal world, the response observed is completely due to the treatment--but in the real world the response observed is due to many things only part of which is the treatment.
• Example: In an experiment, a researcher offers to pay you $5 (the treatment) if you can wiggle your ears. You do so (the response). What contributed to researcher recording your ears as wiggling? A portion of the cause can be allocated to being paid (treatment effect), but some is also due to ability, how you feel that day, whether or not you understood what was being asked of you, whether or not the researcher saw your ears move when you did it (exogenous factors).