Homeowners choose not to refinance their mortgages for any number of reasons. But when they don't, they lose out on tens of thousands of dollars in savings.

Exactly how much they lose depends on each borrower's individual circumstances, but a first-of-its-kind study attempts to quantify what people forfeit by not turning in their old loan rates for lower ones.

Researchers found that the median household, having failed to refinance, gave away $45,000 in savings over the life of its mortgage. The study -- by Benjamin Keys and Devin Pope from the University of Chicago, and Jaren Pope of Brigham Young University -- also found that the mistake of not refinancing is widespread.

Based on a sample of 1.5 million single-family mortgages that were active in December 2010, they estimate that 1 in 5 borrowers -- that is, roughly 300,000 families -- had not refinanced when it appeared profitable to do so.

The findings "suggest that the size and scope of the problem of failing to refinance is large," the researchers said. "While much of the savings a household can receive by refinancing represents a transfer of wealth from investors to households, the foregone savings is clearly significant for each individual household."

Even when controlling the sample for the often-valid reasons borrowers have for sticking with their higher-rate loans, Keys, Pope and Pope found that the losses were just as great, if not more so.

The justifications people have for not refinancing are almost as varied as the borrowers themselves. One factor is that calculating the financial benefit -- or loss -- is relatively complex. Another is that the benefits are not always immediate, but rather accrue over time.

But other factors often are at play. Refinancing can be expensive, often requiring cash out-of-pocket to cover a number of upfront costs.

Sometimes borrowers don't believe the refinancing offers they receive are legitimate. Some don't even open letters from lenders, thinking what's inside is some sort of scam.

In other instances, the borrower's balance is so low that refinancing is seen as not worth the trouble. In other cases, they no longer have the good credit necessary to win approval from lenders. And in yet other cases, they might owe more than their houses are currently worth, meaning they'd have to bring large amounts of cash to the table to gain lower rates.

Absent these factors, though, the authors say, "there are serious consequences for homeowners if they fail to take advantage of refinancing options when interest rates decline."

The typical active loan in the sample was paying 5.52 percent in interest, had 23 years remaining and an unpaid balance of just over $200,000. The average loan-to-value ratio was 74 percent.

The authors estimate that over 91 percent of the households in the full sample would benefit from refinancing -- a percentage they admit is dramatically overstated, since it doesn't allow for homeowners who were planning on moving, those who kept their original loans for tax purposes, and other factors. Allowing for those factors, the researchers calculate that 41 percent of the full sample were in a position where they should have refinanced.

Narrowing the sample even further by weeding out people whose credit scores had declined, whose loan-to-value ratios had increased, and/or who had missed or been late with a mortgage payment reduced the number who should have refinanced to 31 percent. And after removing households that had taken second liens against their properties, the sample was still 20 percent of households in December 2010 who were missing an important financial opportunity.

Worse, perhaps, is that 4 out of 10 of those people were still living in their homes two years later, continuing to make the full and on-time monthly payments, even though rates had continued to decline.

Take a household with a 30-year, fixed-rate loan of $200,000 at 6.5 percent at origination. When rates declined to 4.5 percent between 2008 and 2010, the savings by refinancing over the life of the mortgage is more than $80,000, even after accounting for transaction costs.

When rates reached all-time lows in late 2012, they had dipped to 3.35 percent. So someone with a contract rate of 6.5 percent would save roughly $130,000 by refinancing.

Native-born Americans looking to move into homeownership for the first time could learn a thing or two from immigrant homeowners, according to recent research.

Economists at Rutgers University and the Georgia Institute of Technology found that immigrants leverage "birthplace networks" to come up with money to not only purchase their homes, but also to maintain them during hard times.

Unique to immigrants, birthplace networks are social groups of friends and family from the same country of origin.

The study's authors found that although homeownership rates among immigrants fell between 2000 and 2012, the decline was less severe when compared to native-born homeowners. The hypothesis offered in the study is the ability of immigrants to call on their networks during both good times and bad. And while the theory calls for more study, Americans of all heritages can consider expanding their support networks to include, say, co-workers, fellow churchgoers or club members. The list, in fact, is almost endless.

The trend may be toward walkable communities: those with amenities close enough to residences that automobiles are unnecessary, at least for everyday needs. But traffic and commuting time are still high on the list of concerns for most homebuyers.

"There is no way to solve traffic congestion," Brookings Institution Economist Anthony Downs said at a recent real estate conference. "Congestion is simply an inexorable part of the way cities grow."

No wonder 3 out of every 4 would-be buyers focus at least somewhat on cutting their commuting costs, according to a National Association of Realtors survey. Only 27 percent said they were unconcerned with commuting expenses.

About 14 percent were so troubled that they compromised on the home they bought to be closer to work. Six percent more bought a smaller house to be closer to family, and 2 percent did the same to be closer to schools.

Few would-be buyers ask about the local police or fire departments, at least not directly. But they almost always want to know about the schools.

Normally, you can find what you're looking for from the school in question or the local school district. But here, from the Counselors of Real Estate -- the trade group for the country's 1,100 or so real estate advisors -- are four websites for more detailed school information:

-- greatschools.org. Submit a school name for test scores, course offerings and parent/student reviews. Input an address to see all nearby schools.

-- education.com/schoolfinder. Plug in a school name to see how it compares to others in the district and the state. Also shows boundary maps for each school.

-- publicschoolreview.com. Enter the home's address to find all nearby schools, plus information -- but not test scores -- for each one.

-- privateschoolreview.com. A similar site locates private institutions.

Even though the home-office deduction is said to be a red flag for federal income tax auditors, it is a legitimate write-off for small-business owners who, in fact, have space in their homes dedicated solely to their businesses.

According to the latest Census Bureau data, the practice of working at home is on the upswing. By last count in 2010, the number of us working at home totaled 13.4 million, up from 9.2 million in 1997.

According to IRS data, some $9.8 billion in home office expenses were claimed on IRS Form 8829 in 2011.

The write-off is split into two classes: direct expenses related to the taxpayer, and indirect expenses that apply to the house as a whole and are only partially deductible. About $6 out of every $7 claimed comes from indirect expenses, such as mortgage interest, utilities and repairs.

When it comes to real estate, the appraisal is the linchpin around which all else revolves. Both buyers and sellers are in a holding pattern until the appraiser arrives at the property, looks it over and comes back with a figure on what he thinks the place is worth.

Such is the case whether the property in question is a single-family house in the suburbs or a $200 million office tower in the city.

"Nothing happens in real estate until the appraisal report is signed and an opinion of the property's value is provided," says Brian Coester, an appraiser who presides over his own appraisal management company.

With that in mind, here are some things you should know:

-- There is a major disconnect within the lending business. Some lenders -- and real estate agents -- think the appraiser's job is to get the deal done, whereas appraisers generally think of lenders as money-hungry outfits who don't understand their profession.

According to Coester, CEO of Coester VMS in Rockville, Maryland, the appraiser's job is to be unbiased and completely independent of the transaction, while at the same time being realistic and practical.

-- The appraiser's valuation is her opinion -- repeat, opinion -- of what the property is worth. It doesn't matter what the buyer is willing to pay or what the seller is willing to accept.

"Two appraisers could do an appraisal on the same day, on the same house, come up with two different values and have them both be right," says Coester. "The reality is that value is really the appraiser's opinion, not an average, not a range, but a number the appraiser picks by looking at the data, understanding the market and all factors considered."

If the appraisal comes in too low for the lender to accept the buyer's application for a mortgage, the seller will either have to lower his price or the buyer will have to come up with more cash to make the deal work.

Yet the appraiser's valuation does not have to be the final word. Most appraisal companies offer a step-by-step procedure to follow if anyone involved in the deal thinks the valuation is off-base.

-- The information available determines much of the results. Appraisers are only as good as the data available to them.

Most, but not all, markets have a multiple listing service from which the appraiser gleans much of her information. But issues tend to arise when the appraisal is on new construction or houses in rural areas. Then, the appraiser must often deal with incomplete, inaccurate and outdated data.

Sellers should write up an inventory of all the improvements made to the house within the previous five years, complete with receipts if possible, to present to the appraiser as he enters the house. That way, the appraiser can spend his time verifying the information, which is more likely to reflect favorably upon the overall appraisal.

Remember, though, routine maintenance does not count.

-- You are only as good as your neighborhood. Like it or not, for better or worse, your neighbors and your neighborhood have an overall effect on your home's value. In a $200,000 neighborhood, spending $100,000 on improvements is not likely to add $100,000 in value.

-- At the end of the day, all adjustments to the valuation must be backed by real data that support the appraiser's opinion and would stand up in court.

For example, a $5,000 adjustment for garage space isn't just pulled out of thin air. It is backed by market research and data indicating that garages are worth $5,000 per space. It might be that homes with two-car garages sold for $5,000 more than those with one-car garages, or a variety of other market data.

-- Lenders' guidelines are unclear at best. While all lenders try to adhere to the rules set down by Fannie Mae and Freddie Mac -- the two secondary market companies that purchase loans from primary lenders -- or those from the Veterans Administration and Federal Housing Administration, the variety of requirements and requests lenders ask for can be amazing, according to Coester.

Moreover, most underwriters haven't been properly trained on appraisals, and as result, appraisers are sometimes stuck with requests and requirements that contextually don't make sense in the realities of the market or the appraiser's scope of work.

The Uniform Standards of Professional Appraisal Practice (USPAP) is the one true requirement. USPAP discusses how appraisers go about their business, and is the only thing appraisers are bound to. "Everything else is considered guidelines or suggestions, and varies from client to client," Coester says.

-- Appraising is a full-time profession. The typical appraiser does one or two appraisals a day.

"They are trained to be very careful when it comes to what they will and won't do when it comes to value, property condition and selecting comparables," according to Coester.

-- Appraisers are supposed to be licensed and be familiar with the area in which the subject property is located.

Licenses are hard to come by. According to Coester, "it takes two years, 300-plus tested education hours and 3,000 field hours to obtain an appraiser certification."

You have the right to ask to see the appraiser's credentials and make sure she hasn't traveled from outside the subject market. And if you aren't satisfied, you can ask the lender to send another appraiser.

-- An appraisal is not a home inspection. The two are totally different. The inspector's job is to make sure all the mechanical and subsystems are working and that there are no structural issues. The appraiser's is to observe the house in its current state, compare that with similar homes in the area and come up with a valuation.

Put another way, appraisers typically work on the assumption that everything is in good working order, whereas inspectors verify functionality.