Survivorship bias & backfill bias clarifications

From Kaplan online:
Both survivorship bias (failure to include funds that ceased to exist over the sample period) and backfill bias (adding past results to historical index returns for funds that are added to the index) tend to bias alternative investment index returns upward.

Am I to understand that survivorship bias is when an index does not include funds that stopped operating during a specific period of time?

Further, backfill bias is when an index creator adds past results to the historical return of the same index? i.e. he just changes the index’s return by adding more observations?

Yes, and yes.

In survivorship bias, poorly performing funds drop out, so the index shows only surviving (i.e., well-performing) funds, so there’s an upward bias.

In backfill bias, it’s more likely that the creator will backfill funds with good performance than those with poor performance, so there’s an upward bias.

Excellent explanations as always.

My pleasure.