Bug: Overlapping episode fix can create episodes that are too old for the returns

[MichaelHanksSF]

Depending on how bad the input data is, this piece of code:

# If a child has overlapping episodes, shorten the earlier one decom_next = combined.groupby("CHILD")["DECOM"].shift(-1) change_ix = combined["DEC"].isna() | combined["DEC"].gt(decom_next) combined.loc[change_ix, "DEC"] = decom_next[change_ix]

lines 180-183 in datacontainer.py

can create a DEC which is smaller than the first date of the earliest return. This happens prior to the derivation of datacontainer.data_start_date so it could push this date earlier than it should be. This will have the knock-on effect of the historic graph starting too early and the default transition rates being skewed.

Possible fixes could be:

• calculate datacontainer.data_start_date before this fix is put in plac
• remove episodes that are impacted by code above that have DEC older than oldest return

Probably the second?