A missing value is an absent or unavailable entry for an attribute that an instance is expected to contain. Before training, inspect the data for missing entries and address them during preprocessing so the inputs become suitable for a neural network. section 6.1.3 section 6.2.1
Use missing-value checks as part of a broader data-preparation workflow:
- Explore the dataset before training; numerical features can be examined with histograms, while other data types should be inspected through representative samples. section 6.1.3
- Treat missing-value handling as one step alongside vectorization and value normalization, rather than feeding raw data directly to the model. section 6.2.1
- Include missing-value treatment in dataset curation, together with checking data quality, labels, and feature usefulness. section 5.4.1
A numerical dataset
Suppose a numerical dataset contains feature entries that are absent for some instances. Plotting feature distributions can reveal the issue; those entries must then be dealt with during data preparation before model training. section 6.1.3 section 6.2.1


































