Three authors (Brian Uzzi, Ryon Lancaster and Shannon Dunlap) present tabular data in Laura Empson, ed., Managing The Modern Law Firm: New Challenges New Perspectives (Oxford Univ. Press 2007) at 99. The table shows data for five groups of 133 law firms during 1989-95 organized into quintiles by number of lawyers. For each quintile of size, a column shows the average number of in-house attorneys at their major clients based on National Law Journal league tables.
Starting with the largest quintile, the in-house client average was 53.3 attorneys; the next quintile down had clients with an average of 43.9 attorneys; then up to 49.3; followed by down to 43.5 and the smallest quintile of firms had clients with the smallest average, 34.4 attorneys. The F-statistic for those attorney averages was 5.32. A fairly steady decline, which suggests the intuitive circumstance that bigger law departments retain bigger law firms.