Manual scoring uses the method of reducing the top by 1MP for everyone time the board was unplayed - the concept is that matchpoints are shared with the pair/s who do not play the board.

Computer scoring uses the Neuberg Formula which factors the frequencies and assumes that if the boards had been played more times the scores on the traveller would have been reproduced proportionately - so if a board is played 10 times instead of 11 it assumes that a complete top would have been achieved 1 x 11/10  i.e. 1.1 times.  It then matchpoints on this basis. 

The traditional manual adjustment will tend to flatten scores - i.e. my +1100 scores 13MPs instead of the top of 14. In Neuberg it will 13.something.  Although there are some highly complex mathematical arguments about this sort of factoring it is the generally adopted method throughout international bridge.  You can see the factoring of frequencies directly on the ECatsBridge pages especially on the higher numbered boards which tend to be played less times and so are factored sometimes by 20 or 30 times. 

As far as Scorebridge is concerned, if you look at their webpage you will see that Stephen Bligh advertises Simple and Neuberg scoring.  He explains that if a club wishes to use Neuberg as ECats does all they need to do is uncheck the box in the program that says Simple scoring and then it will factor the frequencies as described.