The phrase "were effective" can be replaced with various synonyms to add variety and depth to your writing. Some alternatives include "proved successful," "yielded positive results," "achieved the desired outcome," "were fruitful," "made an impact," "fulfilled their intended purpose," and "met expectations." By using different phrases to convey the same meaning, you can enhance the readability of your writing and avoid repetition. Experiment with different synonyms to find the most appropriate and engaging language for your project. Overall, using synonyms for "were effective" is an excellent way to add diversity and interest to your work.