How to control the sequence and identify the change

[Ahmet Cakir]

I would like to control the sequence of my variable, in the example data it is Bid.

I want to control by rounds, if the Bid increases/decreases/not change.

How can I evaluate it by observation wise? Suppose that P is from 1301 to 1310 i.e, 10 subjects.

input int P byte(Rd Bid)
1301   1  21
1301   2  63
1301   3 100
1301   4  39
1301   5  58
1301   6  39
1301   7  42
1301   8  52
1301   9  47
1301  10  85
1301  11  75
1301  12  69
1301  13  71
1301  14  73
1301  15  75
1301  16  81
1301  17  63
1301  18  86
1301  19  88
1301  20  91
1301  21  92

[Clyde Schechter]

I'm really not sure I understand what you want. But this:

by P (Rd), sort: gen delta = sign(Bid - Bid[_n-1])

creates a new variable that will be 1 if Bid is increased from its previous value, 0 if it is unchanged, and 1 if it is decreased from its previous value. (And it will always be missing in the first observation because there is no previous observation to compoare to.)

If this is not what you want, please post back with another example, and include hand-calculated results showing what you want, along with a narrative explaining how you did the hand calculation.