QC tests are plotted using which symbol?

The symbol used for plotting QC (Quality Control) tests typically resembles an "X." This symbol is commonly associated with marking points or indicating data in various fields, including statistics, quality analysis, and engineering. In the context of QC tests, using an "X" suggests an observation or data point being plotted on a chart or graph, which is crucial for visual representation of quality control metrics.

Visual plotting is essential for interpreting QC data, as it allows practitioners to quickly identify trends, variances, or issues that may require further investigation. The choice of symbol is important as it needs to be distinct and recognizable to effectively communicate the information represented in the charts or graphs being used for analysis.

Other symbols listed, while they may have their own specific meanings in different contexts—such as "O" for observations or "√" for verification—do not have the same standard association with QC data plotting as the "X" does. Therefore, "X" is the preferred symbol in this scenario for representing plotted QC test data.