Confidence in science is based on transparency, and the ability to reproduce results by repeating experiments. Without access to the raw data generated by, or used in your experiments, your experiments cannot be verified by others.

Given the often high cost of generating data, preserving data for future use can often prove to be far more cost-effective.

The National Science Foundation is now requiring all applicants to submit a detailed plan for preserving and disseminating their research data. I.e., you will not be rewarded a grant from the NSF unless you clearly state your plans for long-term data management.