To accurately evaluate the effectiveness of your design techniques, it's important to observe and analyze how your players respond and how it affects your metrics. You can use playtesting, A/B testing, user reviews, and user behavior data to gain feedback. Playtesting involves inviting a sample of your target audience to play your game and record their reactions, comments, and suggestions. With A/B testing, you can compare the performance of two or more versions of your game or a specific feature or element to see which one yields better results. Additionally, you can read and analyze the comments and ratings that your players leave on your game's website, store, or social media. Lastly, tracking and analyzing the data that your game generates can help identify patterns, trends, and anomalies.