Of course, when a formal stable record is preferred, writing should be an appropriate mode.

当然，如果需要形成正式且持久的记录，书面形式则比较合适。

This is data that would not be found on a paper trail or in any formal financial record.

这些数据不会体现在书面记录或者其他形式的经济记录中。

For instance, when we observe casually, we may not be aware of factors that bias our observations, and, and when we rarely keep formal records of our observations.

例如，我们的观察比较随意，可能没有意识到偏见的因素。还有我们很少对我们的观察做正式的记录。