Hello,   I'm sure this is fairly straight forward but I just can't get my head around how.   I've got a table with a base value for the first record in a category.  All other rows within this category have an adjustment rate.  I want to work out the new value based upon this adjustment rate.  But it's sequential, so row 1 value * row 2 rate = row 2 value, row 2 value * row 3 rate = row 3 value etc.  It's not the easiest thing to articulate, so here's an example.   Starting table Class Month Adjustment_Rate Base_Value Category 1 Jan-18   10.00 Category 1 Feb-18 0.96   Category 1 Mar-18 0.99   Category 1 Apr-18 1.02   Category 1 May-18 1.05   Category 2 Jan-18   15.00 Category 2 Feb-18 0.94   Category 2 Mar-18 1.00   Category 2 Apr-18 1.03   Category 2 May-18 1.03     This is what I want in the end (I'd subsequently drop Base_Value) Class Month Adjustment_Rate Base_Value New_Value Category 1 Jan-18   10.00 10.00 Category 1 Feb-18 0.96   9.60 Category 1 Mar-18 0.99   9.50 Category 1 Apr-18 1.02   9.69 Category 1 May-18 1.05   10.18 Category 2 Jan-18   15.00 15.00 Category 2 Feb-18 0.94   14.10 Category 2 Mar-18 1.00   14.10 Category 2 Apr-18 1.03   14.52 Category 2 May-18 1.03   14.96   I'm assuming I need to use a lag function, e.g. lag Base_Value, but on observation 2 I need to lag the new value.   Thanks in advance!   Edit: Fixing typos. ... View more