Reliability of equipment for measuring the ground hardness and traction

Dara Twomey, Leonie Otago, Shahid Ullah, Caroline Finch

    Research output: Contribution to journalArticlepeer-review

    17 Citations (Scopus)


    The aim of this paper is to report the inter-rater reliabilities and intra-rater reliabilities of the Clegg hammer, penetrometer, and studded-boot apparatus used for measuring the mechanical properties of natural turf, and to determine whether the level of experience influences the reliability. Three experienced and three novice testers measured the surface hardness and rotational traction at nine locations on a community-level Australian football oval. A repeated-measures analysis of variance tested for significant differences between the six testers for all equipment, and intra-class correlation coefficients (ICCs) were calculated to determine the inter-rater reliabilities and intra-rater reliabilities. The ICCs for the reliability between the six testers ranged between 0.77 and 0.87 for the Clegg hammer, ranged between 0.55 and 0.73 for the penetrometer, and equalled 0.51 for the studded-boot apparatus. The inter-rater reliabilities and intra-rater reliabilities were greater for the experienced testers than for the novice testers for the Clegg hammer and penetrometer but the novice testers produced greater inter-rater reliabilities for the studded-boot apparatus. This study highlights the potential variability that can exist between testers using the ground hardness and traction equipment, which has implications for future research involving multiple testers both in agronomic-based studies and in linking the surface properties to the injury risk across multiple venues.

    Original languageEnglish
    Pages (from-to)131-137
    Number of pages7
    JournalJournal of Sports Engineering and Technology
    Issue number3
    Publication statusPublished - Sep 2011


    • Clegg hammer
    • Ground hardness
    • Penetrometer
    • Reliability
    • Rotational traction


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