Table 1

Three research goals and their main characteristics within workload-related sports injury research

	Three goals of research
	To describe	To predict	To draw causal inference
Research objective can be	To describe how athletes perform their training or how many athletes that sustain injury over a given time span	To predict who is at risk of injury (by comparing athlete workloads and characteristics)	To understand why injury occurs (by comparing athlete workloads and characteristics)
Researchers aim to	Describe, not to investigate associations	Investigate an association which is non-causal	Investigate a causal association
Researchers can use	At least one variable in the analysis*	At least two variables in the analysis	At least two variables in the analysis
Role of additional variables	No additional variables are included in the analysis	Subgroup stratification (optional)	Confounders, mediators and/or effect-measure modifiers
Should the analysis be based on frameworks for sports injury occurrence?	No	No	Yes
Some examples of statistical techniques	Regression Cluster analysis …	Regression Classification …	Regression IPW IV-estimation G-estimation G-formula Standardisation …
Type of study	Exploratory or confirmatory	Exploratory or confirmatory	Exploratory or confirmatory
Goal allows researchers	To describe a workload-related or an injury-related variable	To predict which athletes are most vulnerable to injury. These athletes may be target population for interventions.	To identify potential targets for sports injury prevention. Here, authors assess the role of causal factors which if targeted for interventions, are likely to reduce sports injury risk.

Classification includes, but is not limited to, decision trees, random forests, neural networks.
*If the aim is to describe injury development over time, two variables are needed (injury and time). Please note that the term ‘how’, which is used in relation to describing in the table, has previously been used in the context of causal inference in relation to the mechanisms underpinning sports injury occurrence in other educational pieces.20
IPW, inverse probability weighting; IV estimation, Instrumental variable estimation.