european college of sport science

Friday, June 26th, 2009
JS and JF were two most used serve techniques. Nevertheless the use of different serve techniques differs between these three groups so
that JS was used more and JF less when the level of the game was higher. JF was the proportionally most used and most efficient serve
technique in G1. In G2 and G3 JS was the most used technique and it was also quite effective, but it had highest error percentage. So the
high use of JS can be explained partly by the target to score direct points by ace serves.
ADJUSTING REGRESSION STATISTICS TO ASSESS VALIDITY OF MEASURES IN DIFFERENT POPULATIONS
HOPKINS, W.
AUT UNIVERSITY
All concurrent validity studies and most method-comparison studies have a criterion (gold-standard or high-quality) measure for assessment
of another measure, but there is widespread lack of understanding about the best approach to such assessment. The limits-ofagreement
approach assesses interchangeability of two measures, but it provides no rationale for choosing the better measure; moreover,
the systematic lack of agreement known as proportional bias that is often apparent in the Bland-Altman plot (of difference vs mean
of the measures) can be artifactual. Amongst regression approaches, least-squares analysis with the criterion as dependent variable
provides the most useful statistics: the calibration (regression) equation and standard error of the estimate help practitioners interpret
individual measurements taken with the other measure, and researchers can use the correlation coefficient to adjust the magnitude of
effects involving the measure. However, values of the regression statistics can be used directly in these ways only when the sample in the
validity study is representative of the population in the clinical, practical or research setting. I have now derived formulae to adjust the
values for other populations.
I based my approach on the following assumptions: there is a linear relationship between the criterion and other measure; uniform
random error in the other measure contributes to scatter in the relationship between the measure and the criterion; and any random
error in the criterion is uniform and known. The data from a validity study of one population then allow estimation of the random error in
the other measure, from which one can derive the calibration equation, standard error of the estimate and correlation coefficient that
would apply to a population with a different mean and standard deviation of the criterion or the other measure.
One can also derive the standard error of the estimate that would apply to a population with the widest possible range of values (infinite
standard deviation). This error is appropriate for comparing validity of measures studied with samples from different populations, especially
when the measures are in different units (e.g., body fat from a criterion four-compartment model regressed against measures of
skinfolds, body density, or bioimpedance). The calibration equation for this imaginary population is appropriate for assessing proportional
bias when the criterion and other measure are in the same units. Researchers can also adjust the regression statistics to a real
reference population to compare measures.
I simulated validity studies with a spreadsheet to check that the formulae for all adjusted statistics are correct. The formulae are too
complex for analytical derivation of confidence limits, but bootstrapping will provide robust estimates. Use of these adjusted statistics and
their confidence limits should improve understanding and application of validity in research and practice.
CONTENT VALIDITY AND INTERNAL CONSISTENCY OF SELF-ASSESSMENT QUESTIONNAIRE FOR CLIMBING ABILITIES
CHAN, W.K., HORST, E.J., CHENG, Y.Y., NG, J.
1,3,4. THE CHINESE UNIVERSITY OF HONG KONG, 2. MILLERSVILLE UNIVERSITY , USA
Content validity and internal consistency of self-assessment questionnaire for climbing abilities
Introduction: The questionnaire of Self-assessment for climbing abilities was designed by Eric, J. Horst (Horst, 2008) in which eight components
are included, they are climbing experience, technical skills, mental skills, general conditioning, sport-specific conditioning, injury
risk, nutritional habits, and lifestyle and discipline. There is no measurement tool to evaluate sports climbers’ climbing abilities in Asia.
This study investigated the content validity and internal consistency, reliability of Eric’s Self-assessment for climbing abilities questionnaire
for Hong Kong sports climbing participants regarding their perception on their climbing abilities.
Research Methods: The Chinese version of the questionnaire was translated by the research team and which has been assessed by five
climbing coaches in order to check the validity. Only some wordings of the questionnaires have been amended after the assessment.
The questionnaire was distributed to Hong Kong sports climbing participants in different climbing association and sports climbing athletes
in Hong Kong Youth team and the 2008 interschool competition participants. 106 questionnaires have been collected.
Results: 1) This research invited five experienced climbing coaches evaluated the meaning of the translated questions, in order to conduct
a content validity analysis. One of the questions which related to the perception on participants’ bouldering scale level has been set to
answer one more question which made sure that the participant knowing the meaning of bouldering scale.
2) The internal consistency for reliability test as revealed from Cronbach’s Alpha indicated that the eight skill components received poor to
acceptable internal consistencies (r=0.17 – 0.77).
3) Only scores from two subscales had acceptable internal consistencies: Climbing experience = .77, Technical skills = .75. Scores for
other subscales had rather weak internal consistencies: Mental skills = .36, General conditioning = .54, Sport-specific conditioning = .61,
Injury risk = .17, Nutritional habits = .45, Lifestyle and discipline = .46. The low alpha values provide preliminary evidence that some items
in these subscales might be problematic.
Conclusions: It is concluded that some of the components in the Self-assessment for climbing abilities questionnaire demonstrated statistic
and problematic design by the use of Hong Kong climbing participants by the finding of this pilot research. This research has suggestions
for questionnaire modification.
Reference
Horst, E.J (2008). Conditioning for climbers: The compete exercise guide. Connecticut: Falcon.
This study was funded by the Hong Kong Physical Education Assessment Association, Hong Kong SAR.
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