What does a correlation coefficient of 1 indicate in gene expression analysis?

A correlation coefficient of 1 indicates a perfect positive correlation between two variables, in this case, gene expressions. This means that as the expression level of one gene increases, the expression level of the other gene also increases in a perfectly linear relationship. In the context of gene expression analysis, a correlation coefficient of 1 signifies that the two genes have identical expression patterns across the samples analyzed. This implies that they are regulated in the same way, responding similarly to various conditions or stimuli.

For the other options, a correlation coefficient of 0 would suggest no correlation, while a negative correlation coefficient would indicate that one gene's expression increases as the other's decreases. Therefore, both genes being off or behaving oppositely are not represented by a correlation coefficient of 1, confirming that identical gene expression is the accurate interpretation in this scenario.