The document discusses the issue of variable sparsity in deep networks, highlighting that differing sparsity levels in input data can hinder training and affect output consistency. It proposes a method called sparsity normalization to stabilize outputs regardless of input sparsity, leading to improved performance across various datasets including collaborative filtering and electronic health records. Experimental results indicate that sparsity normalization enhances model accuracy and stability, outperforming existing techniques on multiple benchmark datasets.