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@@ -84,9 +84,13 @@ There are three probability axioms:
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\begin{enumerate}
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\begin{enumerate}
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\item \textbf{Expectation - }The weighted average of the probabilities in the sample space
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\item \textbf{Expectation - }The weighted average of the probabilities in the sample space
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\[\sum_{}^{S}{P(A) * A} = E \quad\text{where }E\text{ is the expected value}\]
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\[\sum_{}^{S}{P(A) * A} = E \quad\text{where }E\text{ is the expected value}\]
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\item \textbf{Variance - }The spread of possible values for a random variable
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\item \textbf{Variance - }The spread of possible values for a random variable, calculated as:
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\item \textbf{Standard Deviation - }something
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\[\sigma^{2}=\frac{\sum(X - \mu)^{2}}{N}\]
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\[std = \sqrt{V}\quad\text{where variance is }V\]
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Where \(N\) is the population size, \(\mu\) is the population average, and \(X\) is each value in the population.\\
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For samples, variance is calculated with \textbf{Bessel's Correction}, which increases the variance to avoid overfitting the sample:
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\[s^{2}=\frac{\sum(X - \bar{x})^{2}}{n - 1}\]
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\item \textbf{Standard Deviation - }The square root of the variance, giving a measure of the average distance of each data point from the mean in the same units as the data.
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\[\sigma = \sqrt{V}\quad\text{where variance is }V\]
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\end{enumerate}
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\end{enumerate}
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\subsubsection{Probability Functions}
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\subsubsection{Probability Functions}
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@@ -128,11 +132,9 @@ means will approach the true mean of the population.
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The Central Limit Theorem states that the sampling distribution of a sample mean is a normal distribution even when the
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The Central Limit Theorem states that the sampling distribution of a sample mean is a normal distribution even when the
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population distribution is not normal.
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population distribution is not normal.
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\[
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\[
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\frac{\sqrt{n} \left( \bar{X}_n - \mu \right)}{\sigma} \xrightarrow{d} N(0, 1),
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\frac{\sqrt{n} \left( \bar{X}_n - \mu \right)}{\sigma} \xrightarrow{d} N(0, 1)
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\]
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\[
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\text{Where \( \bar{X}_n = \frac{1}{n} \sum_{i=1}^{n}\), \( X_i \) is the sample mean, and \( N(0, 1) \) is a standard normal distribution.}
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\]
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\]
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Where \(X_i\) is the sample mean, \(N(0, 1)\) is a standard normal distribution, and \(\bar{X}_n = \frac{1}{n} \sum_{i=1}^{n}X_i\).\\
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This is a challenging to understand solely as an equation. As an example, take a sample of two six-sided dice rolls and average their numbers.
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This is a challenging to understand solely as an equation. As an example, take a sample of two six-sided dice rolls and average their numbers.
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The more sample averages taken, the more they will resemble a normal distribution where the majority of samples average around 3.
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The more sample averages taken, the more they will resemble a normal distribution where the majority of samples average around 3.
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@@ -140,6 +142,13 @@ The more sample averages taken, the more they will resemble a normal distributio
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Confidence is described using a confidence interval, which is a range of values that the true value is expected to be in, and its associated confidence level,
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Confidence is described using a confidence interval, which is a range of values that the true value is expected to be in, and its associated confidence level,
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which is a probability (expressed as a percentage) that the true value is in the confidence interval.
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which is a probability (expressed as a percentage) that the true value is in the confidence interval.
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It is important to note that confidence levels, such as 95\%, do not indicate that the real value is within 5\% of the point estimate. The confidence level expresses
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the probability that the real value is in the range provided by the confidence interval.
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At the highest level, calculating confidence intervals is simply the observed statistic (generally the mean) plus or minus the standard error.
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To calculate standard error, kys.
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% Confidence intervals can be calculated with z-tests, t-tests. Go into parametric vs non-parametric
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% Confidence intervals can be calculated with z-tests, t-tests. Go into parametric vs non-parametric
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\subsubsection{Statistical Inference}
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\subsubsection{Statistical Inference}
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