Semiquantitative

Semiquantitative refers to information that provides an estimate of magnitude rather than an exact amount. It sits between qualitative data, which indicates only the presence or absence of a feature, and quantitative data, which yields a precise numeric value. In semiquantitative results, measurements are expressed as categories, grades, or concentration ranges, such as negative, trace, low, medium, high, or as ordinal scales like 1+, 2+, 3+. The intent is to convey relative level rather than precise quantity.

In laboratory and applied settings, semiquantitative methods rely on signals or responses that correlate with amount but do not calibrate to a specific unit. Examples include color intensity on a dipstick, band density on a gel, or visual scores from imaging. These results can be obtained quickly and with minimal equipment, making them useful for screening, point-of-care testing, or rapid triage, where exact quantification is unnecessary or impractical.

Common contexts include clinical immunoassays and lateral flow tests that report semiquantitative readouts; enzyme-linked assays that are read against reference standards; and historical endpoints that estimate copy number in end-point PCR by gel densitometry. In medical imaging, semiquantitative scoring systems assess severity or extent, such as staging or grading scales.

Limitations include reduced precision, susceptibility to operator interpretation and instrument variability, and dependence on assay conditions and reference ranges. Semiquantitative results are typically appropriate for screening or initial assessment but may be supplemented by fully quantitative measurements when exact values are required.