Which of the following best describes multivariate analysis?

Multivariate analysis refers to statistical techniques used to analyze data that involves multiple variables simultaneously in order to understand the relationships and interactions among them. This approach is particularly useful when you want to study how several dependent and independent variables relate to each other and how they influence outcomes. By analyzing multiple variables together, it allows researchers to uncover complex relationships and provide a more comprehensive view of the data.

In contrast, the other choices focus on more limited scopes of analysis. For instance, analyzing a single variable or comparing just two variables does not capture the interactions and relationships that emerging from multiple variables, therefore they do not reflect the essence of multivariate analysis. Additionally, tracking changes over time for a single variable also lacks the multi-dimensional perspective that multivariate analysis offers. Hence, the description that highlights the simultaneous examination of multiple variables aptly captures the main concept of multivariate analysis.