A two-tailed hypothesis is a form of a research hypothesis that states the direction of a relationship between two variables. For example, if the researcher believes that higher levels of education are related to higher levels of income, they would write the two-tailed hypothesis stating: There is a relationship between levels of education and income.
The two tails refer to the two possible outcomes that can be tested by the researcher: that the relationship is either positive or negative. If the researcher believes that higher levels of education lead to higher levels of income, then they would test for a positive relationship. Conversely, if the researcher believes that higher education leads to lower income, then they would test for a negative relationship.
In order to perform a two-tailed hypothesis test, the researcher must first determine the direction of the relationship by collecting data. This involves determining the variables to be tested, and then measuring how they are related. Once this data is collected, the researcher can use statistical methods to test whether there is a significant relationship between the two variables.
The two-tailed hypothesis is an important tool for researchers, as it allows them to test for both positive and negative relationships between two variables. This helps researchers to draw more accurate conclusions about the data they collect, and ensure that their research is valid and reliable.