背后的度量标准：我们如何开发“Time Spent Learning Well”
At Duolingo, we’ve developed a lot of proprietary metrics that help us improve our product in very specific and unique ways. One of the most important metrics that we created is Time Spent Learning Well (TSLW).
在Duolingo，我们开发了许多专有指标，以非常具体和独特的方式帮助我们改进产品。我们创建的最重要的指标之一是学习时间良好（TSLW）。
This isn’t just any metric—it’s an essential quality metric that helps us optimize for learning alongside growth. TSLW has evolved over several years to become the version we use today—let’s look at how we got here, what it measures, and how we use it!
这不仅仅是任何指标，它是一个关键的质量指标，帮助我们在增长的同时优化学习。TSLW经过数年的发展，成为我们今天使用的版本，让我们来看看我们是如何到达这里的，它衡量了什么，以及我们如何使用它！
How we arrived at TSLW
我们是如何得出TSLW的
Since Duolingo is a learning app, we had to find creative ways to approximate teaching efficacy. Our Efficacy Lab conducts rigorous research to measure the efficacy of Duolingo, but these studies aren’t helpful in conducting A/B tests on a daily basis. It’s extremely important that we have a proxy metric for learning, because that’s what we’re here to do! So how did we land on Time Spent Learning Well?
由于Duolingo是一个学习应用程序，我们必须找到创造性的方法来近似教学效果。我们的效果实验室进行了严格的研究，以衡量Duolingo的效果，但这些研究对于每天进行A/B测试并不有帮助。我们必须有一个学习的代理指标非常重要，因为这是我们的目标！那么我们是如何确定学习时间良好的呢？
Total Sessions
We started with Total Sessions, which measured the total number of sessions people were completing (from a path lesson to a Match Madness round to a quick Story review). The idea was more sessions = better for learning. If you do more, you learn more, right? Not quite!
总会话数
我们从总会话数开始，它衡量了人们完成的总会话数（从一个路径课程到一个匹配疯狂回合到一个快速故事复习）。这个想法是会话越多=学习越好。如果你做得更多，你就会学得更多，对吗？不完全对！
We found that Total Sessions was an imperfect metric because session length (time spent doing the activity) was very variable. We wanted learners to advance through their course and encounter harder content, and naturally, harder lessons might take longer. (Not to mention that we want learners to encounter more advanced content—yes, it’s harder, but it’s also new!)
我们发现总会话数是一个不完美的指标，因为会话长度（活动所花费的时间）非常不稳定。我们希望学习者能够在课程中不断进步，遇到更难的内容，而自然而然，更难的课程可能需要更长的时间...