Introduction to Study Skills & Research Methods (HL10040) Measurement Errors Introduction to Study Skills & Research Methods (HL10040) Dr James Betts

Lecture Outline: Measurement Errors Continued Types of Errors Assessment of Error Introduction to Inferential Statistics Chi-Squared tests Assessment Details.

Measurement Errors Virtually all measurements have errors Reliability and Measurement Error are not the same, rather Reliability infers an acceptable degree of Measurement Error.

SD

This total variance can then be ‘partitioned’

Systematic/Random Error % Body-fat Subject 1 Subject 2 Subject 3 Subject 4 Skin-Fold Callipers Hydrostatic Weighing

Assessment of Error Systematic Error

Assessment of Error Random Error

3 points of visual assessment: Assessment of Error Systematic & Random Error 3 points of visual assessment: -Systematic Error: -Random Error: -Nature of error:

Dependent Variable Independent Variable Total Variance between trial 1 & trial 2 Systematic Variance Extraneous/ Confounding (Error) Variables

Smallest Worthwhile Effect

Re-Run

Introduction to Inferential Statistics Before our next lecture you will be conducting some inferential statistics in your lab classes All you need to be aware of at this stage is that the ‘P-value’ represents the probability that total variance is not due to primary variance

Goodness of fit χ2 test SPSS Output

Contingency χ2 test SPSS Output

Selected Reading I know error and variance can be confusing topics, try these: Atkinson, G. and A. M. Nevill. Statistical methods for assessing measurement error (Reliability) in variables relevant to sports medicine. Sports Medicine. 26:217-238, 1998. Hopkins, W. G. et al. Design and analysis of research on sport performance enhancement. Med. Sci. Sport and Exerc. 31:472-485, 1999. Hopkins, W. G. et al. Reliability of power in physical performance tests. Sports Medicine. 31:211-234, 2001. Atkinson, G., ''What is this thing called measurement error?'' , in Kinanthropometry VIII: Proceedings of the 8th International Conference of the International Society for the Advancement of Kinanthropometry (ISAK) , Reilly, T. and Marfell-Jones, M. (Eds.), Taylor and Francis, London , 2003.

Coursework (60% overall grade) Your coursework will require you to address 2 of the following research scenarios: 1) Effect of Plyometric Training on Vertical Jump 2) Effect of Ice Baths on Recovery of Strength 3) Effect of Diet on the Incidence of Muscle Injury 4) Effect of Footwear on Sprint Acceleration 5) Effect of PMR on Competitive Anxiety.

Coursework Outline For each of the 2 scenarios you will need to: Perform a literature search in order to provide a comprehensive introduction to the research area Identify the variables of interest and evaluate the research design which was adopted Formulate and state appropriate hypotheses Summarise descriptive statistics in an appropriate and well presented manner…

Coursework Outline Cont’d… Select the most appropriate statistical test with justification for your decision Transfer the output of your inferential statistics into your word document Interpret your results and discuss the validity and reliability of the study Draw a meaningful conclusion (state whether hypotheses are accepted or rejected).

Coursework Details (see unit outline) 2000 words maximum (i.e. 1000 for each) Any supporting SPSS data/outputs to be appended To be submitted on Tuesday 14th December Assessment Weighting Evaluation & Analysis (30 %) Reading & Research (20 %) Communication & Presentation (20 %) Knowledge (30 %)

Web address also referenced on shared area Coursework Details All information relating to your coursework (including the relevant data files) are accessible via the unit web page: www.bath.ac.uk/~jb335/Y1%20Research%20Skills%20(FH10040).html Web address also referenced on shared area

Mid-Term Test (40% overall grade) NEXT WEEK This test will involve short answer questions covering all the information covered so far Mostly knowledge recall but will require understanding and possibly some calculations Duration = 50 min So…

Mid-Term Test (40% overall grade) Surnames: A-F Arrive promptly at 08.10 am for start of test at 08.15 am Exit in silence afterwards Surnames: G-Z Arrive promptly at 09.10 am for start of test at 09.15 am Exit however you like!