“…A negative relationship is taken as evidence of (presumptively welfare reducing) non-price competition. Indexes of input use often used are the presence of particular technologies , Luft et al, 1986, Robinson et al, 1987, length of stay (Robinson andLuft, 1985, Hersch, 1984), staffing levels and/or mixes (Robinson, 1988, Hersch, 1984, and reserve capacity (Joskow, 1980). A typical finding in this literature is that higher levels of concentration lead to lower levels of input use.…”