Google Data Analytics Professional Certification Practice Test

What is a key characteristic of long data?

1. Each subject is represented in a single row

2. Multiple time points are recorded in a single row

3. Each subject has data in multiple rows

4. Columns are used extensively

The correct answer is: Each subject has data in multiple rows

A key characteristic of long data is that each subject has data in multiple rows. This structure allows for a more flexible representation of data that includes multiple measurements or observations for each subject over time or across different conditions. By arranging the data in this way, analysts can easily perform time-series analysis, track changes, and conduct more complex statistical analyses. In long data formats, the repeated measurements or observations are typically stacked vertically, leading to a higher number of rows compared to wide data formats where each subject’s data is consolidated into fewer rows. This format also aids in the application of various data manipulation and analysis tasks, making it easier to apply functions across different dimensions of the data, such as grouping by subjects or analyzing trends over time. The other options do not capture this defining feature of long data. For instance, representing each subject in a single row is characteristic of wide data rather than long data, where each row is associated with a specific observation or measurement. Recording multiple time points in a single row also reflects a wide data format, as it implies condensing information that long data would represent across many rows. Using columns extensively could describe either format but does not highlight the distinct structure of long data.