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What is the definition of 'Population'?
The entire group of individuals or objects that we are interested in studying.
What is the definition of 'Sample'?
A subset of the population that we actually collect data from.
What is the definition of 'Bias'?
When certain outcomes or responses are systematically favored over others in a study.
What is the definition of 'Confounding Variable'?
A variable that influences both the independent and dependent variables, creating a spurious association.
What is the definition of 'Experimental Units'?
The individuals or objects on which the experiment is performed.
What is the definition of 'Explanatory Variable'?
A variable that is manipulated by the researcher to observe its effect on the response variable.
What are the differences between Observational Study and Experiment?
Observational Study: Researchers observe without intervention, cannot establish causation. | Experiment: Researchers manipulate variables, can establish causation.
What are the differences between Simple Random Sample (SRS) and Stratified Random Sample?
SRS: Every individual has equal chance of selection, may not represent subgroups well. | Stratified: Population divided into subgroups, then random sample from each, ensures subgroup representation.
What are the differences between Cluster Sample and Stratified Random Sample?
Cluster Sample: Randomly select entire groups (clusters). | Stratified Random Sample: Select individuals from all subgroups (strata).
What are the differences between Retrospective and Prospective observational studies?
Retrospective: Looks at past data. | Prospective: Collects data as the study unfolds.
What are the differences between Sampling With Replacement and Sampling Without Replacement?
With Replacement: An item can be selected multiple times. | Without Replacement: Once selected, an item cannot be chosen again.
Explain the concept of Random Sampling.
A method of selecting a sample from a population where each member of the population has an equal chance of being chosen. It reduces bias and allows for generalization.
Explain the concept of Random Assignment.
The process of assigning experimental units to treatment groups randomly. This helps to create roughly equivalent groups at the start of an experiment, reducing the impact of confounding variables.
Explain the concept of Causation vs. Correlation.
Causation means that one variable directly causes a change in another. Correlation means that two variables are related, but one does not necessarily cause the other. Only well-designed experiments can establish causation.
Explain the importance of a Control Group in an experiment.
The control group provides a baseline for comparison. By not receiving the treatment (or receiving a placebo), it allows researchers to isolate the effect of the treatment variable.
Explain the concept of Replication in experimental design.
Replication involves using more than one experimental unit in each treatment group. This increases the statistical power of the experiment and reduces the impact of random variation.
Explain the concept of 'Sampling with replacement'.
Sampling with replacement means that once an individual is selected for the sample, they are returned to the population and can be selected again. This keeps the population size constant.