Example: Relationship between income and age.
Based on the number of variables
|Type of correlation||Definition||Example|
|Simple correlation||A simple correlation aims at studying the relationship between only two variables.||Correlation between height and weight.|
|Partial correlation||In partial correlation, you consider multiple variables but focus on the relationship between them and assume other variables as constant.||Correlation between investment and profit when the influence of production cost and advertisement cost remains constant.|
|Multiple correlations||Multiple correlations aim at studying the association between three or more variables.||Capital, production, Cost, Advertisement cost, and profit.|
Based on the direction of change of variables
|Type of correlation||Definition||Example|
|Positive correlation||The two variables change in a similar direction.||If fat increases, the weight also increases.|
|Negative correlation||The two variables change in the opposite direction.||Drinking warm water decreases body fat.|
|Zero correlation||The two variables are not interrelated.||There is no relationship between drinking water and increasing height.|
Correlation research design is used when experimental studies are difficult to design.
It is used to identify the association between two or more variables.
You can select the issues according to the requirement of your research. There are three common types of problems as follows;
You need to select the sample carefully and randomly if necessary. Your sample size should not be more than 30.
There are various types of data collection methods used in correlational research. The most common methods used for data collection are as follows:
Surveys are the most frequently used method for collecting data. It helps find the association between variables based on the participants' responses selected for the study. You can carry out the surveys online, face-to-face, and on the phone.
| It’s cost-effective.|
Easy to conduct.
You get quick responses.
| Responses may not be reliable or dishonest.|
Some questions may not be easier to analyze
In the naturalistic observation method, you need to collect the participants' data by observing them in their natural surroundings. You can consider it as a type of field research. You can observe people and gather information from them in various public places such as stores, malls, parks, playgrounds, etc. The participants are not informed about the research. However, you need to ensure the anonymity of the participants. It includes both qualitative and quantitative data.
Archival data is a type of data or information that already exists. Instead of collecting new data, you can use the existing data in your research if it fulfils your research requirements. Generally, previous studies or theories, records, documents, and transcripts are used as the primary source of information. This type of research is also called retrospective research.
Suppose you want to find out the relation between exercise and weight loss. You can use various scholarly journals, health records, and scientific studies and discoveries based on people's age and gender. You can identify whether exercise leads to significant weight loss among people of various ages and gender.
| The researcher has control over variables.|
Easy to establish the relationship between the cause and effect.
Inexpensive and convenient.
Easy to replicate.
| The artificial environment may impact the behaviour of the participants.|
The short duration of the lab experiment may not be enough to get the desired results.
Suitable for trend analysis and identification.
An ample amount of existing data is available.
| You need to manipulate data to make it relevant.|
Information may be incomplete or inaccurate.
The association between cause and effect is called causation. You can identify the correlation between the two variables, but they may not influence each other. It can be considered as the limitation of correlation research.
You’ve found that people who exercise regularly lost maximum weight. However, it doesn’t prove that people who don’t use will gain their weight. There could be many other possible variables, such as a healthy diet, age, stress, gender, and health condition, impacting people's weight.
You can’t find out the causation of your research problem. Still, you can collect and analyse data to support the theory. You can only predict the possibilities of the method, phenomena, or a problem you are studying.