bortfald

Bortfald is a Danish term used to describe the absence or nonappearance of something within a defined context. The word denotes omission or dropout and is applied in several fields to refer to missing elements, whether data, participants, or components of a text or speech. While most common in Danish usage, the concept appears in other Nordic languages with related meanings.

In statistics and survey research, bortfald refers to missing data or nonresponse. It can be classified as unit bortfald, where whole survey cases are missing, or item bortfald, where individual questions remain unanswered. Causes include nonresponse from individuals, lost follow-up in longitudinal studies, refusals to participate, or problems during data collection. Researchers analyze bortfald rates and patterns to assess potential biases.

The implications of bortfald are important: missing data can reduce statistical power and, if systematic, introduce bias into results. Handling bortfald often involves strategies such as following up with nonrespondents, applying weighting adjustments, employing multiple imputation, or using model-based approaches to account for missingness. Study designs may also aim to minimize bortfald through improved contact methods and respondent engagement.

In linguistics and philology, bortfald can describe the omission of a sound, syllable, or morpheme in speech or in historical texts. This sense reflects processes of elision, simplification, or orthographic convention rather than data attrition.

Etymologically, bortfald combines bort meaning away and fald meaning fall or drop, capturing the idea of something that has fallen away or been left out. The term is standard in Danish statistical and social research contexts and is used with similar meaning in neighboring Nordic languages.