1. Preparing to Analyse Data C.Adithan Department of Pharmacology JIPMER Pondicherry - 605006

2. NominalProportion Categorical OrdinalScores, Ranks Continuous NumericalInterval Discrete Types of Data Categories of Measurement

3. Nominal scale: e.g., Male, Female Hindu, Muslim, Christians - Expressed in proportions (60% male, 40% female) Ordinal scale: e.g., Mild, Moderate, Severe pain Light, average, heavy, very heavy smokers - Expressed as Scores and Ranks Data can be arranged in an ORDER and RANKED

4. Interval/Ratio scale:  Highest order of the measurement  Assume equal intervals in its measurement Interval scale: - Does not have an absolute zero point e.g., Temperature on the centigrade scale Ratio scale: - Has an absolute zero point e.g., blood sugar For Statistics Interval and Ratio Scales are treated as SAME

5. Analysis of Data: Consider 4 specific aspects  Checking of Data  Missing Data  Outliers - Affect Mean  SEM; Regression analysis  Transformations - logarithmic - Square root - reciprocal

7. Outlier r value With outlier: 0.65 Without outlier : 0.07

9. Summary Statistics:  Arithmetic mean  Mode  Median  SD  SEM  Proportion  Confidence Interval (C.I.)

10. Measures of Central Tendency  Arithmetic mean: Sum of all values divided by Number of observations  Mode Most common value observed  Median Value that comes half-way when the data are ranked in order 1 2 3 4 5 5 8 Mean= 28/7 = 4, Mode=5, Median=4 1 2 5 3 4 5 8

11. Measures of Dispersion  Range: Difference between lowest and highest scores in a set of data  SD: describes the variability of observations about the mean  SEM: describes the variability of means 80, 70, 80, 5, 2, 3,1 Range=80-1=79 80, 6, 7, 30,12, 2,1 Range=80-1=79 80, 70, 80, 5, 2, 3,1 S.D.= 34.4 ± 39.7 80, 6, 7, 30,12, 2,1 S.D.= 19.7 ± 28.3 80, 70, 80, 5, 2, 3,1 SEM= 34.4 ± 15.0 80, 6, 7, 30,12, 2,1 SEM= 19.7 ± 10.7

12. Measures of Dispersion Confidence Interval Describes the limit within which 95% of mean values, if determined in similar experiments are likely to fall Lower limit = mean – (t 0.05 x SEM) Upper limit = mean + (t 0.05 x SEM) 80, 70, 80, 5, 2, 3,1 95 % C.I. = 34.4 (-2.2, 71.1) 80, 6, 7, 30,12, 2,1 95 % C.I. = 19.7 (-6.5, 45.9)

13. Rounding of Numbers 85.345 85.364 17.750 17.850 85.348074 85.35 85.3 85.4 85.3 85.35 17.8