A Universe is simply a collection of ticker symbols (stock symbols, cryptocurrency symbols, etc.) When you backtest a trading model, you can either run the model against a single symbol, or against a universe.
If you have a free membership, you can backtest against the two basic universes provided on Quantacula.com:
If you have opened a model created by another Quantacula member, you may also notice the custom universe that the model creator saved with their model. You can backtest with this custom universe even with a free membership.
If you have a premium membership then you can create your own custom universes, selecting the symbols that you desire. Go to the My Universes page from the main menu to work with your custom universes.
Quantacula.com currently offers end of day data for the US stock market, and cryptocurrencies. To specify a cryptocurrency symbol, append a .USD to the end (for example, Bitcoin is BTC.USD.) You can also use cross-crypto currency symbols like BTC.ETH.
With a premium membership you also gain access to the intelligent premium universes. These universes dynamically represent the following market indices:
Unlike a static custom universe, whose symbols remain consistent throughout a backtest, the premium universes contain special logic that ensure that the symbols that were currently in the index at any point in time are applied in a backtest. The dynamic nature of these universes eliminates the problem of survivorship bias.
Survivorship bias occurs when you pick a group of symbols based on some current information (such as the current composition of the Dow 30) and backtest using this group of symbols beginning at an earlier date. Since the best performing stocks are typically added to a market index, survivorship bias invariably leads to artificially inflated backtest results that you'd have little hope of duplicating in live trading.