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Analysis of Distribution If the sample is truly random and there is no bias in the sampling then the expected distribution would be a smooth bell-shaped.

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Presentation on theme: "Analysis of Distribution If the sample is truly random and there is no bias in the sampling then the expected distribution would be a smooth bell-shaped."— Presentation transcript:

1 Analysis of Distribution If the sample is truly random and there is no bias in the sampling then the expected distribution would be a smooth bell-shaped curve. However, factors can enter the sampling to affect the shape of the distribution curve. PopulationSample Random Sample Sample size > 30 for each sub-group Each sub-group has Equal numbers of individuals

2 Normal Distribution Curve

3 Task In this topic you will be trying to compare the sample distributions of two subgroups taken randomly form a population to determine whether there is enough evidence to answer you question and whether the sample trends will occur in the population also! PopulationSample Random Sample Sample size > 30 for each sub-group Each sub-group has Equal numbers of individuals

4 Mass Of Trout in South Taranaki Rivers Kaupokanui RiverWaingongoro River FREQENCY%FREQENCY% FREQENCY%FREQENCY% Mass In Grams

5 Describing Feature of the Distribution Clusters: Concentration of data around specific values Skewness: When the Median and Mean are not aligned Outliers: Values that lie outside the boundaries of the distribution

6 Summary Statistics Minimum Lower Quartile Median Upper Quartile Maximum Mean Standard Deviation

7 Skewness

8 Outliers An outlier is an observation that lies an abnormal distance from other values in a random sample from a population. In a sense, this definition leaves it up to the analyst (or a consensus process) to decide what will be considered abnormal. Before abnormal observations can be singled out, it is necessary to characterize normal observations.

9 Outliers An outlier is an observation that lies an abnormal distance from other values in a random sample from a population. In a sense, this definition leaves it up to the analyst (or a consensus process) to decide what will be considered abnormal. Before abnormal observations can be singled out, it is necessary to characterize normal observations.


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