Introduction to Parametric Techniques
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Online Course Pharmaceutical Biostatistics Chapter 4: Parametric Techniques
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Statistical Analysis
Parametric “parametric”=parameter or characteristic of a population. -t-tests -Analysis of variance • Normally distributed •More robust than nonparametric test
Non-parametric Less “fussy”. Less sensitive -Ideal for use when you have data that are measured on nominal (categorical) and ordinal (ranked) scales. -small samples -data do not meet the stringent assumptions of parametric techniques. -Also known as distribution free tests 17/7/2017
Online Course Pharmaceutical Biostatistics Chapter 4: Parametric Techniques
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Parametric vs Non-Parametric Tests
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Two types of statistical techniques used to generalize data from samples to population.
1.
Parametric: Data must be at least interval (continuous / scales) and the distribution must be NORMAL.
2.
Non-parametric: The data is at least interval but the distribution is not NORMAL or the data is categorical (nominal / ordinal).
Online Course Pharmaceutical Biostatistics Chapter 4: Parametric Techniques
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Parametric vs Non-Parametric Tests Parametric test
Non-parametric test
-Data: Ratio (eg: distance,in kilometer) and Interval (eg: oC)
- Data: Nominal(eg: race, gender) and ordinal (eg: satisfaction)
- Normally distributed
- Not Normally distributed
- Based on mean and standard deviation
-Based on frequency and median
Test: • t-tests •ANOVA •Pearson correlation
Test: • Chi-Square-For nominal • Mann-Whitney U, Kruskal-Wallis H, Wilcoxon T, Friedman and Correlation Spearman
17/7/2017 Online Course Pharmaceutical Biostatistics Chapter 4: Parametric Techniques
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Classification of Univariate Technique
Interval/Ratio Data
One sample
Independent
-Z/t test -One-way ANOVA
2 or more samples
Related
-Paired samples t-tests - Repeated measure
Nominal/ Ordinal Data
One sample
2 or more samples
Independent
Related
-Chi Square -Mann Whitney -Median -K-S -K.W ANOVA 17/7/2017
Online Course Pharmaceutical Biostatistics Chapter 4: Parametric Techniques
-Sign -Wilcoxon -McNemar 5
MEASUREMENT SCALE Measurement scale
Examples
RATIO Has a meaningful zero point (physical)
-Height -Weight -Time -Speed
INTERVAL Predetermined equal intervals, no true zero point
-Score: Achievement, IQ, Temperature
ORDINAL Classifies and ranks objects
Opinion: Academic level, income level, degree of liking
NOMINAL Classifies objects into categories
True Categories: Taste, gender, ethnicity, color Artificial Categories : Color type (soft, bold) Weather (hot, cool) 17/7/2017
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Online Course Pharmaceutical Biostatistics Chapter 4: Parametric Techniques
Characteristics of Normal Distribution
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Two types of statistical techniques used to generalize data from samples to population.
1.
Parametric: Data must be at least interval (continuous/ scales) and the distribution must be NORMAL.
2.
Non-parametric: The data is at least interval but the distribution is not NORMAL or the data is categorical (nominal/ordinal). Online Course Pharmaceutical Biostatistics Chapter 4: Parametric Techniques
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Skewness and kurtosis must be zero for normal distribution
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Online Course Pharmaceutical Biostatistics Chapter 4: Parametric Techniques
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