Cover -- Title Page -- Contents -- Preface -- Foreword to Students -- 1 INTRODUCTION -- 1.1 What do we mean by statistics? -- 1.2 Why is statistics necessary? -- 1.3 The limitations of statistics -- 1.4 Calculators and computers in statistics -- 1.5 The purpose of this teXt -- 2 HEALTH CARE INVESTIGATIONS: MEASUREMENT AND SAMPLING CONCEPTS -- 2.1 Introduction -- 2.2 Populations -- 2.3 Counting things - the sampling unit -- 2.4 Sampling strategy -- 2.5 Target and study populations -- 2.6 Sample designs -- 2.7 Simple random sampling -- 2.8 Systematic sampling -- 2.9 Stratified sampling -- 2.10 Quota sampling -- 2.11 Cluster sampling -- 2.12 Sampling designs - summary -- 2.13 Statistics and parameters -- 2.14 Descriptive and inferential statistics -- 2.15 Parametric and non-parametric statistics -- 3 PROCESSING DATA -- 3.1 Scales of measurement -- 3.2 The nominal scale -- 3.3 The ordinal scale -- 3.4 The interval scale -- 3.5 The ratio scale -- 3.6 Conversion of interval observations to an ordinal scale -- 3.7 Derived variables -- 3.8 Logarithms -- 3.9 The precision of observations -- 3.10 How precise should we be? -- 3.11 The frequency table -- 3.12 Aggregating frequency classes -- 3.13 Frequency distribution of count observations -- 3.14 Bivariate data -- 4 PRESENTING DATA -- 4.1 Introduction -- 4.2 Dot plot or line plot -- 4.3 Bar graph -- 4.4 Histogram -- 4.5 Frequency polygon and frequency curve -- 4.6 Scattergram -- 4.7 Circle or pie graph -- 5 CLINICAL TRIALS -- 5.1 Introduction -- 5.2 The nature of clinical trials -- 5.3 Clinical trial designs -- 5.4 Psychological effects and blind trials -- 5.5 Historical controls -- 5.6 Ethical issues -- 5.7 Case study: Leicestershire Electroconvulsive Therapy (ECT) study -- 5.8 Summary -- 6 INTRODUCTION TO EPIDEMIOLOGY -- 6.1 Introduction -- 6.2 Measuring disease.

6.3 Study designs - cohort studies -- 6.4 Study designs - case-control studies -- 6.5 Cohort or case-control study? -- 6.6 Choice of comparison group -- 6.7 Confounding -- 6.8 Summary -- 7 MEASURING THE AVERAGE -- 7.1 What is an average? -- 7.2 The mean -- 7.3 Calculating the mean of grouped data -- 7.4 The median - a resistant statistic -- 7.5 The median of a frequency distribution -- 7.6 The mode -- 7.7 Relationship between mean, median and mode -- 8 MEASURING VARIABILITY -- 8.1 Variability -- 8.2 The range -- 8.3 The standard deviation -- 8.4 Calculating the standard deviation -- 8.5 Calculating the standard deviation from grouped data -- 8.6 Variance -- 8.7 An alternative formula for calculating the variance and standard deviation -- 8.8 Obtaining the standard deviation and sum of squares from a calculator -- 8.9 Degrees of freedom -- 8.10 The Coefficient of Variation (CV) -- 9 PROBABILITY AND THE NORMAL CURVE -- 9.1The meaning of probability -- 9.2 Compound probabilities -- 9.3 Critical probability -- 9.4 Probability distribution -- 9.5 The normal curve -- 9.6 Some properties of the normal curve -- 9.7 Standardizing the normal curve -- 9.8 Two-tailed or one-tailed? -- 9.9 Small samples: the t-distribution -- 9.10 Are our data 'normal ? -- 9.11 Dealing with 'non-normal data -- 10 HOW GOOD ARE OUR ESTIMATES?95 -- 10.1 Sampling error -- 10.2 The distribution of a sample mean -- 10.3 The confidence interval of a mean of a large sample -- 10.4 The confidence interval of a mean of a small sample -- 10.5 The difference between the means of two large samples -- 10.6 The difference between the means of two small samples -- 10.7 Estimating a proportion -- 10.8 The finite population correction -- 11 THE BASIS OF STATISTICAL TESTING -- 11.1 Introduction -- 11.2 The eXperimental hypothesis.

11.3 The statistical hypothesis -- 11.4 Test statistics -- 11.5 One-tailed and two-tailed tests -- 11.6 Hypothesis testing and the normal curve -- 11.7 Type 1 and type 2 errors -- 11.8 Parametric and non-parametric statistics: some further observations -- 11.9 The power of a test -- 12 ANALYSING FREQUENCIES -- 12.1 The chi-squared test -- 12.2 Calculating the test statistic -- 12.3 A practical eXample of a test for homogeneous frequencies -- 12.4 One degree of freedom - Yates correction -- 12.5 Goodness of fit tests -- 12.6 The contingency table - tests for association -- 12.7 The 'rows by columns (r x c) contingency table -- 12.8 Larger contingency tables -- 12.9 Advice on analysing frequencies -- 13 MEASURING CORRELATIONS -- 13.1 The meaning of correlation -- 13.2 Investigating correlation -- 13.3 The strength and significance of a correlation -- 13.4 The Product Moment Correlation Coefficient -- 13.5 The coefficient of determination r2 -- 13.6 The Spearman Rank Correlation Coefficient rs -- 13.7 Advice on measuring correlations -- 14 REGRESSION ANALYSIS -- 14.1 Introduction -- 14.2 Gradients and triangles -- 14.3 Dependent and independent variables -- 14.4 A perfect rectilinear relationship -- 14.5 The line of least squares -- 14.6 Simple linear regression -- 14.7 Fitting the regression line to the scattergram -- 14.8 Regression for estimation -- 14.9 The coefficient of determination in regression -- 14.10 Dealing with curved relationships -- 14.11 How we can 'straighten up curved relationships? -- 14.12 Advice on using regression analysis -- 15 COMPARING AVERAGES -- 15.1 Introduction -- 15.2 Matched and unmatched observations -- 15.3 The Mann-Whitney U-test for unmatched samples -- 15.4 Advice on using the Mann-Whitney U-test -- 15.5 More than two samples - the Kruskal-Wallace test.

15.6 Advice on using the Kruskal-Wallace test -- 15.7 The WilcoXon test for matched pairs -- 15.8 Advice on using the WilcoXon test for matched pairs -- 15.9 Comparing means - parametric tests -- 15.10 The z-test for comparing the means of two large samples -- 15.11 The t-test for comparing the means of two small samples -- 15.12 The t-test for matched pairs -- 15.13 Advice on comparing means -- 16 ANALYSIS OF VARIANCE - ANOVA -- 16.1 Why do we need ANOVA? -- 16.2 How ANOVA works -- 16.3 Procedure for computing ANOVA -- 16.4 The Tukey test -- 16.5 Further applications of ANOVA -- 16.6 Advice on using ANOVA -- APPENDICES -- AppendiX 1: Table of random numbers -- AppendiX 2: t-distribution -- AppendiX 3: χ2 -distribution -- AppendiX 4: Critical values of Spearman s Rank Correlation Coefficient -- AppendiX 5: Critical values of the product moment correlation coefficient -- AppendiX 6: Mann-Whitney U-test values (two-tailed test) -- AppendiX 7: Critical values of T in the WilcoXon test for matched pairs -- AppendiX 8: F-distribution -- AppendiX 9: Tukey test -- AppendiX 10: Symbols -- AppendiX 11: Leicestershire ECT study data -- AppendiX 12: How large should our samples be? -- Bibliography -- Index.