“…There is a direct, or variety, effect of the number of channels on quality, which is positive but not increasing. On the other hand, there is an indirect, or interference, effect of the number of channels on quality by way of the reduced separation between channels, which is negative (Freyens & Jones, ). Furthermore, up to a critical number of channels, say , the positive variety effect is assumed to dominate the negative interference effect (see also Freyens & Jones, ).…”