Regulatory analyses, the internal control mechanism imposed on federal rule makers eight years ago and reinforced by an executive order from President Reagan last year, have been used inconsistently and sometimes are inadequately documented, according to a General Accounting Office study released yesterday.

The study, prepared at the request of Sen. William V. Roth (R-Del.), one of the chief proponents of regulatory reform legislation this year, also faulted the secretive procedures of the Office of Management and Budget, which was given the authority last year to oversee rule-making activities and which has been criticized by activist groups for offering a behind-the-scenes forum for industry executives who want to change proposals.

"OMB generally avoids putting its comments on pending rules in writing. It is therefore generally impossible to determine what role OMB plays in any given rule-making," the report said. "While the agency that issued the rule remains formally accountable for the regulatory decision, it is impossible to determine to what extent the rule-making decision is made in the agency . . . or in OMB." The GAO also noted that the OMB frequently waived the requirement for a regulatory impact analysis, particularly when the administration was trying to reduce regulation.

"We are concerned that so many major rules were allowed to be issued without benefit of a regulatory impact analysis," said the study. "We do not believe that agencies are likely to take the value of regulatory impact analyses seriously if the analysis requirement is frequently waived."

As originally designed, the regulatory analysis was supposed to give agency decision-makers a thorough look at the costs and benefits of a particular proposal, compared to possible alternatives. But, said the GAO study, "many of the analyses failed to consider relevant alternatives to the proposed regulations, failed to identify the various benefits and costs, or failed to compare the costs and benefits of different alternatives."

Nonetheless, the GAO said, "While regulatory analyses provide only part of the required information for decision-making, we believe they can make an important and useful contribution in bringing about more efficient and effective regulation.