Is there reliable data for the success rates of different methods of learning/reviewing vocabulary? I.e.:
- no reviewing
- hand-written flashcards
- SRS flashcard apps
- Goldlist method
Your question can't be answered directly.
I've read some scientific articles about efficiency of learning. I've always looked for experimental results. Most common experiments are performed on remembering flash-cards. How can you compare number of flash-card recalled after 1 week with recalling of facts from listening an audio book?
In that way you are unlikely to see scientific article that compare performance of Pimsleur audio-lingual method with SRS method. Because you can't compare meters with kilograms in scientific way.
On the other hand Jeffrey Karpicke, AltheaBauernschmidt - Spaced Retrieval. Absolute Spacing Enhances Learning Regardless of Relative Spacing, 2011 research shows that massed learning (in single massive session) is far worse then spaced repetition, and that pattern of repetition has no any effect on learning. Their learners learned 25 Cherokee words and were asked for words after one week. With massed learning 25% of words were recalled, with spaced repetition 75%.
The larger the number of repetition and the larger the total learning period the better knowledge is retained in memory. Learning for one year you get better result than if you are learning for one month. Learning once a day you get better results than if you were practicing once a week.
I guess there's no universal way for learning new words. Everyone is different: some people need to write down a word, other people need to hear the word etc. I have been learning foreign languages for years and here are some points one should keep in mind: