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## EMA - Calculation Method
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The EMA calculation utilizes a weighting multiplier, typically denoted as the smoothing factor ($alpha$). This factor is calculated as:
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$alpha = \frac{2}{period + 1}$
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where 'period' represents the chosen period for the EMA.
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The general formula for EMA required for arithmetic operations:
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$EMA_n = (data_{n} \times alpha) + (EMA_{n-1} \times (1 - alpha))$
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or in optimized form (requires only three arithmetic operations instead of four):
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$EMA_n = {alpha}\times ({data_{n}} - EMA_{n-1}) + EMA_{n-1}$
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When calculating the Exponential Moving Average (EMA) and there is not enough data (n < period), several approaches can be considered. Each method has its own pros and cons:
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#### 1. Assume all previous values were 0
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$EMA_0 = 0$ \
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$EMA_n = alpha \times (data_n - EMA_{n-1}) + EMA_{n-1}$
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- Will lead to significant underestimation of EMA in early periods
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#### 2. Calculate as if all previous values were the same as the first value
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$EMA_0 = data_0$ \
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$EMA_n = alpha \times (data_n - EMA_{n-1}) + EMA_{n-1}$
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- Will overestimate early EMA if initial data point is far from representative
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#### 3. Use SMA instead of EMA for the first period
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$EMA_n = \left\{ \begin{array}{cl}
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\frac{1}{p}\left( data_{n}-data_{n-p}\right)+SMA_{n-1} & : \ n \leq period \\
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{alpha}\times ({data_{n}} - EMA_{n-1}) + EMA_{n-1} & : \ n > period
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\end{array} \right.$
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- Creates a discontinuity when switching from SMA to EMA
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### Conclusion
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The choice of method depends on the specific requirements of the application:
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- Method 1 is suitable for applications where underestimation in early periods is acceptable.
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- Method 2 is beneficial when a smooth transition is crucial and the initial data point is representative.
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- Method 3 is appropriate when simplicity is preferred and a clear distinction between SMA and EMA is acceptable.
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- Method 4 offers a good balance between adaptability and maintaining the EMA concept, but may require additional explanation to users.
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