index date

USAGE SUMMARY

The phrase "index date" is correct and usable in written English.
It is typically used in contexts such as research, clinical trials, or data analysis to refer to a specific date that serves as a reference point for an event or observation. Example: "The index date for the study was set as the date of the first diagnosis of the condition."

✓ Grammatically correct

Science

Human-verified examples from authoritative sources

Exact Expressions

60 human-written examples

dAt index date.

The Journal of Headache and Pain

bTime from first recorded migraine diagnosis to index date.

The Journal of Headache and Pain

Patients' first date of therapy was considered their index date.

Journal of Ophthalmic Inflammation and Infection

For controls, index date was the day of the interview.

Plosone

cDiagnosed before the index date.

BMC Gastroenterology

aAge at diagnosis index date.

BMC Medical Research Methodology

‡In year before index date.

British Medical Journal

* Age measured at index date.

Child and Adolescent Psychiatry and Mental Health

Each participant was assigned an index date.

British Medical Journal

Results were calculated for each index date.

BMJ Open

bIn year before the index date.

BMC Gastroenterology

Expert writing Tips

Best practice

When using "index date" in research papers, clearly define how the date was selected (e.g., first diagnosis, admission date) to ensure reproducibility and clarity.

Common error

Avoid using "index date" loosely; always specify the event that makes it the point of reference. For example, don't say 'analyze data around the index date' without stating what makes that date significant for the analysis.

Linguistic Context

The primary grammatical function of "index date" is that of a noun phrase, often used as a subject or object within a sentence. It identifies a specific point in time serving as a reference, such as in research or data analysis, as shown by Ludwig.

Expression frequency: Very common

Frequent in

Science

100%

Less common in

News & Media

0%

Formal & Business

0%

Encyclopedias

0%

Ludwig's WRAP-UP

The phrase "index date" is a noun phrase commonly employed within scientific and research contexts to denote a specific reference point in time. As supported by Ludwig, its primary function is to establish a clear temporal marker for consistent data analysis. The term maintains a Formal and Scientific register, predominantly appearing in academic publications. While "index date" is very common in scientific literature, understanding its precise definition—the event or time serving as the study's anchor—is crucial for preventing misinterpretations. Alternatives such as "reference date" or "baseline date" may be suitable substitutions depending on the nuance required.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

reference date

Focuses on the function of the date as a point of reference, which is more general than a specific event.

baseline date

Emphasizes that the date serves as a point of comparison for later data, commonly used in studies.

start date

Highlights the initiation of a process or study, making it a slightly more action-oriented term.

initial date

Suggests the beginning of a series or sequence, highlighting the starting point.

anchor date

Implies that the date provides a stable reference to which other events are related.

designated date

Highlights that the date was specifically chosen for a particular purpose or study.

study initiation date

Specifically refers to the date when a research study or experiment begins.

enrollment date

Used when referring to the date a participant enters a study or program.

qualifying date

Refers to a date that determines eligibility or inclusion in a dataset or study.

event date

Emphasizes the occurrence of a significant event, such as a diagnosis or treatment.

FAQs

How is "index date" typically used in research?

The "index date" serves as a reference point for longitudinal studies, marking the start of observation or the occurrence of a key event. Data before and after this date are analyzed to understand trends and outcomes.

What can I say instead of "index date"?

You can use alternatives like "reference date", "baseline date", or "initial date", depending on the specific context.

Why is defining the "index date" important in a study?

Defining the "index date" is crucial for ensuring consistent data analysis and interpretation. It standardizes the starting point for all subjects, enabling meaningful comparisons.

What factors influence the choice of an "index date"?

The choice of an "index date" depends on the research question. It might be the date of diagnosis, the start of treatment, or another relevant event that marks a significant point in the study.