What does this equation mean?

and, treating quantization error as uniformly distributed over one step, the resulting quantization noise power has a root-mean-square value of q / $\sqrt{12}$ . This is the textbook derivation behind every “effective number of bits” figure a converter data sheet reports, and it is the reason oversampling helps: spreading the same quantization noise power across a wider sampled bandwidth before filtering it back down effectively lowers the in-band noise floor without changing the converter’s physical resolution. This is analysis grounded in a standard result, not a claim from either vendor’s marketing copy — both data sheets report measured effective noise in microvolts or nanovolts RMS directly, and those measured numbers are what a systems designer should budget against, not the nominal bit count printed on the package.