Which of the following is a method used in hypothesis testing?

The Chi-squared test is a statistical method frequently used in hypothesis testing to determine whether there is a significant association between categorical variables. It compares the observed frequencies in each category to the frequencies expected under the null hypothesis. This test is particularly useful in scenarios such as testing relationships in contingency tables or examining the goodness of fit for a distribution.

In contrast, the other methods listed serve different purposes. Linear regression is primarily used for modeling the relationship between a dependent variable and one or more independent variables, rather than testing hypotheses. Factor analysis is a technique aimed at identifying underlying relationships between variables and reducing data dimensionality rather than forming or testing hypotheses. Multivariate analysis involves observing and analyzing more than one statistical outcome variable at a time, but it is not directly a method of hypothesis testing. Each of these methods has its own applications but does not fit the specific purpose of hypothesis testing like the Chi-squared test does.