There can be 3 types of missing data
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Not Measured |
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Truly missed |
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Wrongly placed |
Some methods that can be used to deal with missing data are:
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Leave as it is |
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Ignore the instance with the missing value(s), i.e. remove the instance |
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Manually enter the missing value, assign a default value depending on the most implicit meaning |
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Replace by statistical values, such as majority, most likely, mean, nearest neighbor, etc. |