in Statistical Study
Identifying the question
- What is the question? (What are my hypotheses?)
- Is it possible to answer the question with statistics?
- Is the data obtainable? (birth weight, socio economic, drugs,
- Is it ethical to obtain such data?
- If not, is there a reasonable substitute?
- Are the assumptions reasonable?
- Identify the population of interest
- Obtain a representative sample of that
- Simple Random Sampling
- Stratified Sampling (M-F, Age groups)
- Systematic Sampling (class roster,
- Convenient Sampling
- Sources of Bias
- Selection bias (undercoverage)
- Non-response bias (day phone)
- Response bias (people lie)
- Observational Studies
- Used when a designed experiment is not
- Subjects studied over a period of time
in natural setting
- Record Variables of interest
- Confounding is a major issue
- Designing an Experiment
- Researcher has control over the subjects
or units in the study
- An intervention takes place that
otherwise would not occur
- Randomization used to assign treatments
- Strongest case for causality
- EDA - Exploratory Data Analysis (trends, relationships,
- Pilot Study
- Identify variables
- Identify types of variables
- Identify Limits of measurement or observation
- Descriptive statistics: present frequency distribution tables
- Inferential statistics: use of proper procedures and
techniques to infer population parameters and relation.
- Check the assumptions behind the procedures and techniques.
Conclusions and Discuss Limitations
- Report and interpret the results of the analysis and answer
the original hypotheses.
- Explain the limitations of the study.
- Identify conclusions that the study could not make.
- Identify new questions arise from this study.