Correlation vs Regression:

Correlation:
- Correlation is a statistical measure that describes the degree to which two variables are related to each other.
- It shows the strength and direction of a relationship between two variables.
- Correlation does not imply causation.

Regression:
- Regression is a statistical technique used to understand the relationship between a dependent variable and one or more independent variables.
- It helps in predicting the value of the dependent variable based on the values of the independent variables.
- Regression analysis can be used to identify the strength and direction of the relationship between variables.

Sampling Techniques:

Simple random sampling:
- Simple random sampling is a basic sampling technique where each member of the population has an equal chance of being selected.
- It is a random and unbiased method of selecting a sample from a population.

Stratified sampling:
- Stratified sampling involves dividing the population into subgroups or strata based on certain characteristics.
- Samples are then randomly selected from each stratum to ensure representation of all groups in the population.

Systematic sampling:
- Systematic sampling involves selecting every nth member from a list of the population.
- It is a simple and efficient method of sampling that ensures a random selection process.

Multi stage sampling:
- Multi stage sampling involves using a combination of different sampling techniques in multiple stages.
- It is useful when the population is large and diverse, allowing for more efficient sampling.

Population vs Sample vs Census vs Sample survey vs Sampling frame:
- Population: The entire group of individuals or items that a researcher is interested in studying.
- Sample: A subset of the population selected for research purposes.
- Census: A study that collects data from every member of the population.
- Sample survey: A study that collects data from a sample of the population to make inferences about the entire population.
- Sampling frame: A list of all the members of the population from which a sample is drawn.