The patchy credit histories of subprime and low-documentation borrowers made it hard to model default rates accurately.
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"I think that fact alone will make the Amazon model hard to clone, " says Bill Gurley, a partner with Hummer Winblad Venture Partners.
The Ricoh model was hard to install, its lousy support and manuals were no help, and the drive's performance was only so-so.
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Whether he follow this model remains hard to predict, particularly because temptations will increase to turn to brawn over brain as he confronts economic and national security crises and becomes familiar with the tools that Bush left behind.
The EMC Academic Alliance works hard to follow this model, partnering with more than 700 colleges and universities in more than 40 countries across the world developing curricula to educate the next generation of cloud architects and data scientists.
France already has Europe's biggest Muslim population, and it is finding it hard to reconcile its model of integration, which relies on a strict separation of religion and state, with demands by French Muslims for religious expression within public institutions.
Barbara Manuel at East Dorset District Council said the model took "hard work and dedication".
This model is really hard to implement because faculty is part time and temporary and thus marginally attached to the school.
The company has built a business model that is hard to replicate, partly because it does engineering, sales, installation and maintenance in-house.
InVision reckons there are 3, 400 sawmills worldwide big enough to benefit from their machines, and is pushing hard to develop a production model.
Even if News Corp does start charging and others follow suit, analysts say doing a U-turn on the free news model will be hard to pull off.
Germany did not become a role model by being hard-headed.
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We are seeing a series of experiments with different MMO monetization models at present, but all have the same problem: games which cost as much as or more than a full-sized game are hard to fund with a model best applied to small, repetitive mobile and social games.
When you have a healthy business model, it is hard to make those changes.
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Our model packed a 20GB hard drive, a 6X DVD-ROM drive, and a standard 100MB Zip drive.
As you know, business model innovation is very hard but also where the greatest rewards are gained.
Online games, in particular the social kind, are hard for firms steeped in this model to make, argues Kristian Segerstrale, the boss of Playfish, the number two in social gaming.
You know, French people are used to not working that hard and still keeping a social model that gives them a lot of security if they lose their jobs, if they're sick, if they're old, if they're ill.
That brings us to Brooklyn in October, where plenty of early model Smarts are wedged in hard-to-come-by alternate side parking spaces.
But it is hard to see his ingenious neo-medieval model working smoothly.
He did seem a role model of self-discipline and hard work, however, saying he improved by challenging better players, swearing off junk food for all but a few days a years and cross-training.
The source of the rich pay packages was the Fannie business model that Mr. Frank fought so hard to protect.
The new PS3 will come in 3 models including extended built in Hard Disk Drive (HDD) capacity of 500GB model and 250GB model, and a newly added 12GB flash memory model initially for Europe only.
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But if it is simply bolted on to add transactional friction to prevent churn (through recurring billing), it will be hard to lined up the rest of the business model to address the other issues previously mentioned.
Quality free-to-play shooters are hard to come by, but CCP believes in the model.
That left Tower with the have-it-all-in-stock business model, the go-to source for hard-nosed music enthusiasts.
Owners of the Audi 5000 model claimed back then that no matter how hard they stood on the brakes, the cars took off by themselves, sometimes with unspeakably tragic, fatal results.
More hard-boiled analysts want solid evidence of a sustainable business model that can be defended from competition, and that the manifold costs of acquiring and keeping the customers is really affordable.
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