Can I use Improvise to pay for activated abilities?

Question

The card Inspiring Statuary states:

Nonartifact spells you cast have improvise.

From the Comprehensive Rules (Ixalan (September 29, 2017))

702.125a Improvise is a static ability that functions while the spell with improvise is on the stack. “Improvise” means “For each generic mana in this spell’s total cost, you may tap an untapped artifact you control rather than pay that mana.”

From the Comprehensive Rules I understand that I can tap artifact to pay {1} of the spells cost. However does the same apply for activated abilities with {X} mana cost on permanents on the field. Example: Mirage Mirror

{2}: Mirage Mirror becomes a copy of target artifact, creature, enchantment, or land until end of turn.

Answer 1

No. Improvise only works for casting spells. Activating abilities, while similar is not casting a spell, thus it cannot be paid for with Improvise.

111.1. A spell is a card on the stack. As the first step of being cast (see rule 601, “Casting Spells”), the card becomes a spell and is moved to the top of the stack from the zone it was in, which is usually its owner’s hand. (See rule 405, “Stack.”)

112.1b An ability can be an activated or triggered ability on the stack. This kind of ability is an object.