• r doesn’t distinguish between explanatory and response variables (that is, it doesn’t matter what you call x and what you call y)
• r is NOT resistant (that is, it IS affected by outliers) Use with caution if outliers appear r measures only the strength of a LINEAR relationship
• r is not affected by units of measurement (e.g changing from kg to lbs using a linear transform)
• r has no units – that is, r is dimensionless