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Bus Stat Notes For Exam Skewness Mean = Median – Symmetric Distribution Mean > Median – Positive Skewness Mean < Median – Negative Skewness Median – Middle Value (divide number of participants by 2) 50% of values are equal to or higher than the median, and 50% are equal to or lower Decrease In Mean -‐Decrease in standard deviation (as the range of hours watched per week has decreased, each of the observations are now closer together and so standard deviation would decrease accordingly (can occur when outlier is removed) Correlation 1 = perfect positive linear relationship -‐0.134 = weak, negative relationship 0 = No correlation -‐1 = negative relationship Between Groups and Within Groups -‐between groups source of variation is the amount of variation in the data that is explained by belonging to a group -‐E.g. measure of the standard deviation between the average reading test score of each TV watching group and the average reading test score of the whole sample -‐Within groups source of variation is the amount of variables in the data that is not explained by belonging to a particular group