The statistical problem is straightforward. To claim an agent adds nine percent you would have to sell the same house twice under different agents, which nobody can do. What such studies actually compare are different houses in different conditions, and any honest analysis would need to control for neighbourhood, property type, condition, price band and month. The Saskatchewan REALTORS Association publishes market data, not agent performance claims, and that distinction is worth keeping in mind.
That does not mean the agent makes no difference. Pricing accuracy, preparation, photography, negotiation and managing the condition period all move the final number, and they move it most in the first two weeks a listing is live. The effect is real. The precise percentage attached to it in an advertisement is not.
Judge the specific claims in front of you instead. Ask which sold comparables were used, what adjustments were made and why, what the recommended price range is rather than a single figure, and what you net after commission and legal fees of $800 to $1,500. Joel Dyck's hand-reviewed valuation shows the reasoning, including the improvements no online estimate could see, so you can assess the argument rather than the slogan.