Doublets will have twice as much area under the curve as singlets, and so on. Most triplets can be split into a singlet band and a doublet band, for example. If you see a minimum between bands in a multiplet, try to manually split it into singlets. In large bands, it is sometimes hard to see multiplets. If the counts are way off, check Fig.
Bands look like horizontally long, rounded rectangles.
Watch out for flecks of dirt that absorb dye and are sometimes called bands by the computer. If lane is severely overloaded, the singlet trend may rise into the intensity region of 3 or 4, according to Fig.3. Just look for the singlet trend yourself - if the dot follows the singlet trend, no matter what the intensity rating, it is a singlet. Watch out for very large bands that are not as intense as the singlet trend would predict. These may be fragments that were not completely cut up.