Whenever you add a property, an area of 2 km radius is created. (*)
Your listing will be automatically compared with the properties located within this area and having the same characteristics: room type and bedrooms.
You can change your area's preferences in the Settings tab. If you desire so, you can make your area bigger or smaller. This will affect the number of properties your listing is compared with.
You can also decide whether you want to compare your property with properties of the same or different kind. Maybe you are renting only one room in your house but you want to compare it to entire apartments. Notice that in cases like this, there might be a high decalage in prices.
Finally, you can change the number of rooms. Even if your property has only one room, you can compare it with properties that have 2 or more rooms.
(*) if there are not enough properties within this radius, the area will become bigger until we have enough properties to compare it with.