1. What Is Economic Impact Analysis?
Essentially, it is change analysis.
The changes that can be measured differ depending on the software tool used.
It seeks to answer the “what if” and “but for” questions.
I.e. what if this change happened? Or what would the economy be like but for the event or business I am trying to measure?
Economic impact differs from but is related to economic contribution.
Both require counterfactual thinking

2. Economic Impact vs. Contribution?
An Economic Impact Analysis estimates the economic impact (in terms of jobs, labor income, taxes, etc.) of a change in the local economy.
E.g. the expansion/entry or contraction/exit of a business like the newly- constructed (and still expanding) Desert Diamond West Valley Casino in Glendale
An Economic Contribution Study describes the portion of the economy (in terms of jobs, labor income, taxes, etc.) supported by an existing business, sector, or program.
E.g. economic contribution of Talking Stick Resort in Scottsdale
From IMPLAN

3. From Transactions to Impacts
Every transaction in a economy is a cause to one or more effects. E.g.
Spending by one is the income of another.
Exporting goods and services is the same as importing money.
Tourism is an export service.
The same dollar can be spent multiple times in the same year which causes a multiplication of economic impacts.
Resources are finite so all spending is a choice to not spend on something else. This is called opportunity cost and it is important in understanding the economics of casinos.
When introducing a casino, money that customers spend comes at the expense of other spending. These offsetting forces do not necessarily zero out the impacts of casinos but do reduce their net benefits.

4. Casinos, Monetary Flows, and the Economy
Wages and benefits to workers
Spending by households, businesses, and governments (local, tribal, state, and federal)
Purchases from vendors
Customer Spending
Dividends
Taxes and revenue sharing