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t statistics, Correlation, Hypothesis Test t Statistic - Coggle Diagram
t statistics
Alternative to Z score
A shortcoming of Z-scores is that they usually require more information than is usually available. We must know the value of standard deviation.
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We can use the formula for sample variance and sample standard deviation to estimate the standard error.
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T Statistic is used to test the hypotheses about an unknown population when the value of standard deviation of the sample is unknown.
Distribution
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you can compute the t statistic for every sample and the entire set of t values will form a t distribution
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Correlation
Why is correlation
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Prediction
If a valuable is unknown, it is possible to use the other variables to make a prediction
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Interpreting correlation
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To describe how accurately one variable predicts the other, you must square the correlation
One of the most common errors in interpreting correlations is to assume that a correlation necessarily implies a cause-and-effect relationship between the two variables.
correlation within this restricted range could be completely different from the correlation that would be obtained from a full range
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A partial correlation measures the relationship between two variables while controlling the influence of a third variable by holding it constant
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Hypothesis Test
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The alternative hypothesis is “Yes. There is a real, nonzero correlation in the population.”
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For a directional test, a positive value for the sample correlation would tend to refute a null hypothesis stating that the population correlation is not positive.
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Correlation and Z-Scores
The Pearson correlation measures the relationship between an individual’s location in the X distribution and his or her location in the Y distribution
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