Which questions needed improvement to generate useful data (e.g. in terms of the way the question was phrased or response validation)?

As an AI, I don't have access to the specific questions you're referring to. However, I can provide general guidance on how to evaluate and improve survey questions.

1. Clarity: The question should be clear and easy to understand. Avoid using jargon, complex words, or long sentences. If respondents don't understand the question, they can't provide accurate answers.

2. Unbiased: The question should not lead respondents towards a particular answer. Avoid using loaded or leading questions.

3. Specific: The question should be specific enough to get the information you need. Avoid asking vague or overly broad questions.

4. Relevant: The question should be relevant to your research objectives. Irrelevant questions can confuse respondents and waste their time.

5. Response options: If the question is closed-ended, make sure the response options are exhaustive and mutually exclusive. Respondents should be able to find an option that accurately represents their answer, and each option should be distinct from the others.

To identify which questions need improvement, you could look for questions that violate these principles. For example, if a question is confusing or leading, or if respondents frequently skip it or choose "I don't know", it may need to be revised. You could also conduct cognitive interviews or pilot tests to get feedback on the questions.