All these economists did was use a custom Altman z-score algorithm according to their methodology, which is linear algebra and statistics. It's a decent predictor of bankruptcy for solely manufacturing companies, of which Sony is not. That's part of their business, the rest's in finance, for which this algorithm's basis is inappropriate and inaccurate as a metric. It's also dependent on how they bin their data, etc. for a variety of parameters that determine the score.
The reason it's so poor a metric for Sony's financial aspects has to do with stochastic fluctuations that directly affect their financial business making a time-series analysis a more appropriate metric. Before I read this blog, I knew *none* of this. I just used your links and Google to do some research. I'm only a mathematician, so I don't know finances per se. All I know is that their given metric is not well suited to predicting Sony's future based on my brief readings. Thus, I'm not terribly concerned from this report based on what I just learned. -Peace