As the saying goes, "correlation is not causation." Correlation is when two (or more) variables show related trajectories. While this could indicate a causal relationship, there may be other unknown or hidden factors at play.
The careful design of experiments can help rule out some factors, however human rights groups should be extremely cautious and rigorous about making rights claims using correlations.
Similarly, when drawing trend lines, the way the line fits the data points can often depend on the variables included in the equation. Depending on the program used for the visualization, it may be possible to modify the trend line's equation and make sure to isolate only the relevant variables and control for alternative influencing factors.