METHODOLOGY OF RESEARCH IN SPORT Goran Sporis, PhD.

Classification of variables Variable label Type Measure Classification for analysis decisions Gender String Nominal Categorical Weight Numeric Scale Continuous Sprint 5 meter

Choosing a statistic when there is one outcome variable Type of variable Number of times measured in each participant Statistics Binary Once Descriptive statistic; Frequencies Twice McNemar’s chi-square Continuous Test for normality, One sampe t-test Paired t-test Three or more Anova

Choosing a statistic when there is one outcome variable and one explanatory variable Type of outcome variable Type of explanatory variable Number of levels of the categorical variable Statistic categorical both values are binary Chi-square Logistic regression continuous Categorical variable is multi-level and ordered Spearman’s correlation coefficient Explanatory variable is binary Independent sample t-test

Choosing a statistic when there is one outcome variable and one explanatory variable Type of outcome variable Type of explanatory variable Number of levels of the categorical variable Statistic continuous categorical Explanatory variable has three or more categories Analysis of variance No categorical variables Regression Pearson’s correlation No outcome variable Both noncontinuous and categorical Categorical variables can have two or more levels Factor analysis

Parametric vs. non-parametric statistic Parametric test Non-parametric equivalent Mean and standard deviation Median and inter-quartile range Pearson’s correlation coefficient Spearman’s or Kendall’s correlation coefficinet Two sample t-test Wilcoxon rank sum test Independent t-test Mann-Whitney U or Analysis of variance Mann-Whitney U test Repeated measures analysis of variance Friedman’s ANOVA test

Some rules for reporting numbers In a sentence, numbers less than 10 are words; In a sentence, number 10 or more are numbers; Try and avoid starting a sentence with a number; Use a zero before the decimal point when the number is less than 1 (e.g. the P value was 0.012); Do not use a space between a number and its per cent sign; Use one space between a number and its unit (179 cm); Report percentage to only one decimal place if the sample size is larger than 100; Report percentage with no decimal place if the sample size is less than 100; P values between 0.001 and 0.05 should be reported to three decimal places. P values shown on output as 0.000 should be reported as <0.0001.

Scientific writing: From time immemorial, it has been known that the ingestion of an “apple” (i.e., the pomme/fruit of any tree of the genus Malus, the said fruit being usually round in shape and red, yellow, or greenish in color) on a diurnal basis will, with absolute certainity, keep a primary member of the health care establishment absent from one’s local environment.

An apple a day keeps the doctor away

Databases Medicine: Medline Biology: BIOSIS Previews (Biological abstracts) Physics: INSPEC Chemistry: Chemical abstracts Economy: EconLit Information/library science: LISA Psychology: PsychINFO Sociology: Sociological Abstracts Philosophy: Philosopher’s Index Languages: Modern language abstracts Kinesiology: Medline, SportDiscus, SCI;

US Nat. Lib. Med. – 24,000 journals, index in Medline 4,000. Science Citation Index (SCI): 5,600

Number of citations in 2010 on articles published in 2009 and 2008 Impact factor Number of citations in 2010 on articles published in 2009 and 2008 IF2010 = Number of articles published in 2009 and 2008

Research power Experiment Cohort study DBRCT RCT CT Cross section study Case series Case report Quality of research