To paraphrase Tolstoy, all fair salary systems are alike; all inequitable systems are inequitable in their own ways. For instance, you might believe that salary compression or salary inversion exists at your institution, because you suspect that current salaries within your unit are artificially low compared to:

• other faculty members in the same discipline but at different institutions (i.e., market inequity);
• other faculty members in different but comparable disciplines at your own institution (i.e., institutional inequity); or
• other faculty members within the same discipline at the institution (i.e., departmental inequity).