[coldtea]

You keep using this word, proportional. I don't think it means what you think it means.

"having a constant ratio to another quantity"

Inversely proportional too is a mathematic relationship with specific meaning (for one the product must be a constant). It doesn't just mean "more pesticide, less ants" (that's a more general statement than inversely proportional).

Perhaps you merely meant correlated with respect to the rent. But even so, in this thread there were so many provisos added, that the relationship is nebulous at least.

[AnthonyMouse]

The relationship we're actually talking about is proportional using your definition. Rent is proportional to housing prices, all else equal.

If all else isn't equal, i.e. you change interest rates or tax rates, then you're changing the constant. But they're still proportional with the new constant. You're only changing the ratio, not the nature of the relationship.