With the Census Bureau working overtime to deliver the 2020 Census by the end of the year and the Supreme Court set to consider whether the Trump administration can exclude undocumented immigrants from congressional representation, a group of experts is warning that “radical transparency” is needed to ensure the public will trust the final outcome.

The share of Americans who doubt the accuracy of the census grew from 24 percent in early March to 31 percent by late July, according to a list of recommendations and comments addressed to bureau Director Steven Dillingham from the Census Scientific Advisory Committee (CSAC), a group of demographers, statisticians and other experts who discussed the statistics at a virtual meeting Thursday.

Michael Cook, Census Bureau spokesman said, “We are currently reviewing the recommendations received from our Census Scientific Advisory Committee. We will respond to them in due time.”

The count has endured unprecedented challenges, including pandemic-related delays, natural disasters, high employee attrition rates, shifting deadlines and litigation over its truncated schedule and President Trump’s attempt to block undocumented immigrants from being counted when House seats are reapportioned.

Several lawsuits have challenged Trump’s attempt, calling it illegal and unconstitutional. Three federal courts have blocked it, including a three-judge panel in Maryland last week, and a fourth is expected to rule. The Supreme Court is scheduled to hear arguments on the matter Nov. 30.

Meanwhile, a federal court in California has enjoined the government from delivering a state population count to the president by the statutory deadline of Dec. 31; on Friday the judge in that case set trial for March. Even after the numbers are delivered to and released by the president, a court could order the government to redo data processing or reopen data collection in a geographically targeted way.

Census data is also used to determine state redistricting and $1.5 trillion a year in federal funding.

As the bureau scrambles to condense its post-data-collection analysis from six months to 10 weeks, the government has indicated it might not meet the December deadline but will try to deliver the data as close as possible to it. The timing is key because if Trump is to give Congress a population count that omits undocumented immigrants, he must do so before he is set to leave office Jan. 20.

But the condensed schedule worries experts, who say vital quality-control measures have been dropped in the rush to produce numbers by the deadline. The government has also not explained how it plans to identify and count undocumented immigrants, for whom no complete or accurate lists exist.

Noting that the count “has been through the wringer,” CSAC Chair Allison Plyer said Thursday that without more openness about its data collection and processing, “the bureau risks even greater declines in response rates across its many surveys going forward.”

Enumerators have described chaotic scenes, as some supervisors ordered them to cut corners or falsify data in order to mark households as counted and meet the target threshold of 99 percent. An amended complaint in the California case includes allegations by enumerators who said they were told to break rules in order to increase productivity. The bureau has denied that it systematically falsified records.

The CSAC recommendations, which echo concerns voiced by the American Statistical Association, also raised questions about the speed with which the count was completed in storm-wracked Louisiana as the Oct. 15 end date for door-knocking approached:

“As of October 15, Louisiana had reached only 98.5 percent enumerated. Then as of Oct. 16 . . . the Bureau reported that Louisiana suddenly reached 99 percent enumeration.” The Associate Director for Decennial Census Programs later explained that this sudden jump in Louisiana on October 16th was based on using ‘high quality administrative data.’ ”

But the recommendations noted that standard procedure is to attempt one or more visits, then rely on such data; if no such data exists, enumerators would return to the address or seek out a proxy. “Filling in a large number of addresses on October 16th with administrative data suggests those addresses may have had no high quality administrative data,” the document said. “CSAC is concerned these final addresses in Louisiana instead were completed with lower quality administrative data.”

The Census Bureau did not immediately reply to questions about the recommendations. In a Nov. 5 post on its website, Deputy Director Ron Jarmin said it was “premature to definitively describe the quality of the 2020 Census or assess its fitness for use” and that “we’ve not uncovered anything so far that would suggest that the 2020 Census will not be fit for its constitutional and statutory purposes.”

Jarmin suggested that improved technology and higher employee productivity had allowed the bureau to mitigate the challenges to this year’s count.

But to Terri Ann Lowenthal, a former staff director of the House census oversight subcommittee, that explanation was not reassuring. “The increase in enumerator productivity, far from increasing my confidence about the quality and accuracy of data collected in the field, raises concerns that enumerators had to rush through their work,” she said.

The Trump administration’s delay of presidential transition activities could further imperil the eventual production of acceptably accurate census numbers, Lowenthal added. “It sustains a lack of transparency,” she said, “potentially allowing political appointees at the Census Bureau or Commerce Department to obscure any shortcuts that might affect the apportionment counts in ways that do not meet the bureau’s own quality standards.”

President-elect Joe Biden’s agency transition team for the Commerce Department includes former chief U.S. statistician Nancy Potok and Denice Ross, a senior fellow at the National Conference on Citizenship who has called for greater openness from the bureau.

The Census Scientific Advisory Committee called on the bureau to release information such as the percentage of occupied households that were enumerated by administrative data and the quality of that data; the percentage counted using proxies such as neighbors or landlords; the percentage missing some information; and the percentage that remained unresolved after door-knocking ended.

It also recommended that the bureau take the six months it originally planned for the post-count analysis, work with outside researchers who can help assess data quality, and release state population counts to the public on the same day it releases them to the president — a decades-long tradition that Commerce Secretary Wilbur Ross has said he will honor.

“Being transparent, ‘warts and all,’ about challenges and limitations has the desired effect of building credibility and loyalty,” the document said. “CSAC recommends that Bureau leadership and communication staff avoid the temptation to gloss over the ‘warts’ of the 2020 Census process and data, and instead focus on providing an unprecedented level of transparency.”