There’s more to the U.S. economy than the occupant of the Oval Office, but you might not know that looking at confidence surveys.

Since the election of President Donald Trump, consumer confidence and business sentiment surveys have been scrambled like never before along partisan lines. Confidence among Republicans has soared while it has crumbled for Democrats, even though most measures show little change in how the actual economy is behaving.

“When you see how the partisan details have changed in recent months it really makes you question the usefulness of these data,” Jim O’Sullivan, chief U.S. economist of High Frequency Economics, said of confidence metrics. “If you’re a consumer, your spending depends primarily on your income and your wealth and your credit.”

Measures of consumer confidence are widely followed economic indicators, due to their correlation over time with consumer spending and the strength of the economy. Large downturns in confidence tend to coincide with economic downturns, and vice versa. Now, surveys designed to ask about the economy resemble a Rorschach test; people see the president and their view of him in everything.

Gallup’s measure of economic confidence among Republicans has increased dramatically since before the election. The difference between those who said they weren’t optimistic and those who said they were optimistic was 46% in October. By January that flipped: The optimists outnumbered the pessimists by 27%. That reversal sent the confidence index for Republicans up 73 points. The index for confidence among Democrats dropped 23 points over this period.

Eight years ago, when President Barack Obama had just taken office, the confidence index among Democrats climbed just 13 points in the same three-month window, while Republican confidence fell just 6 points.

Looking back even further is the University of Michigan’s survey of consumer sentiment. Republican expectations are at an index reading of 120 this month. Since 1952 the overall sentiment index has never topped 112. Democrats, by contrast, were at 55.5, a level not seen since the worst of the financial crisis, when the economy was shedding more than 2 million jobs per quarter. Thus, by Michigan’s measure, Republicans are collectively counting on the best economy in post-World War II history, while Democrats expect something as bad as the worst days of the 2008 financial crisis.

Taken at face value, one would expect heavily Republican areas of the country to strengthen as this confidence leads to a surge in spending and investment, while mostly Democratic areas would weaken for the opposite reasons. Few economists expect such an outcome or see signs that it’s emerging.

“If you look at the swings, before and after the election, they’re not yet substantiated by many real changes in the economy,” said Gregory Daco, head of U.S. economics for Oxford Economics.

Most Americans have their economic fortunes tied to their job, and nearly all workers have the same job now as before the election. Only about 3.5% of Americans switched jobs in November and December and started a new one, according to Labor Department data. Wages have been rising somewhat faster over the past year, but most of those gains have been eaten by also-rising inflation.

Some measures of economic sentiment may be capturing something quite different than in the past.

“Our level of confidence is a function of our perceptions of certainty and control,” said Peter Atwater, president of Financial Insyghts, a research firm studying social mood and confidence. Republicans may be responding to a sense of relief that somebody with a worldview similar to their own has control of the White House, and vice versa for Democrats. “It isn’t always economic factors that drive our mood,” said Mr. Atwater.

Sentiment is especially buoyant at small businesses. An index of small-business optimism from the National Federation of Independent Businesses has climbed 57 points since before the election. Yet the increase in the share of small businesses planning to increase their hiring was more modest, and there’s been little increased planning for greater capital investment, according to the survey.

Three big drivers of business enthusiasm have been hopes for corporate tax reform, less regulation and the prospect of major infrastructure spending that could flood manufacturers and construction firms with work. Treasury Secretary Steven Mnuchin has said that tax reform could take until August. Regulations could also take years to roll back. Meantime, the details of an infrastructure package have yet to emerge, and even once enacted such projects take a notoriously long time.

Investors, like Republicans, are inferring in Mr. Trump a high probability of success despite obstacles he faces. The stock market is up more than 10% since the election. Andrew Liveris, chief executive of Dow Chemical Co., participated in a roundtable of business leaders who met with Mr. Trump last week. Afterward, he said “to have the U.S. government speak the language of business is a completely new experience.”

In the end, expectations will need to square up with the economy’s real performance.