Longitudinal survey design - step by step

A longitudinal survey design studies the same subjects over a period, observing changes or developments in their responses.

Chat icon

Longitudinal Survey Design

A longitudinal survey is a powerful tool for tracking changes over time in specific variables. This type of survey is particularly useful for monitoring progress or deterioration in various aspects being studied. It plays a crucial role in identifying trends and patterns within the responses, which can offer valuable insights into the dynamics of the subject matter.

Furthermore, longitudinal surveys are instrumental in cause-effect analysis. By comparing data collected before and after certain interventions, it becomes possible to analyze causal relationships between these interventions and their outcomes. This approach is essential for understanding the long-term effects of various actions and strategies.

The initiative's longitudinal surveys would necessitate meticulous design to accurately gauge social impact over time. Longitudinal survey must have -

  1. Clear Objectives: Establish goals aligned with the broader social impact objectives.
  2. Consistent Methodology: Uphold consistency in data collection to ensure comparability and reliability.
  3. Participant Engagement: Foster an environment for participant engagement to mitigate attrition rates.
  4. Data Quality Checks: Conduct regular checks to ascertain data accuracy and completeness.
  5. Ethical Considerations: Adhere to ethical standards ensuring participant privacy and confidentiality.

The framework for conducting effective surveys includes understanding different types of questions and their respective advantages. Open-ended questions are significant for gathering rich data as they provide detailed insights. They are particularly useful because they allow respondents to freely express themselves, ensuring that the responses are unbiased and reflect their true opinions or experiences.

On the other hand, closed-ended questions offer benefits like the ease of analysis due to their quantifiable nature. These types of questions are efficient in terms of the time required for respondents to answer and in the analysis phase, making them a practical choice for many survey contexts.

Lastly, the framework emphasizes the importance of understanding the impact dimensions of any intervention or study. These dimensions include

  1. What: Identifies the type of outcome (positive or negative) and its importance to stakeholders.
  2. Who: Determines which stakeholders are affected and their level of underservice.
  3. How Much: Measures the scale, depth, and duration of the impact on stakeholders.
  4. Contribution: Assesses the enterprise's role in achieving the outcomes compared to what would happen otherwise.
  5. Risk: Evaluate the likelihood of the impact differing from expectations.

How to design effective longitudinal study questions?

When crafting questions for a longitudinal study, adhere to these best practices to enhance the quality of responses and boost response rates.


  • Do not repeat: If you already have data such as demographics, do not ask in the baseline survey. Just make sure to include a Unique ID. Also, do not need to ask the same question in the exit line.
  • Unique ID: Incorporating Unique IDs and minimizing question repetition enhances the accuracy and reliability of the survey data, crucial for tracking responses over time and reducing survey fatigue. By adhering to these best practices and key fields in designing longitudinal surveys, stakeholders can better apprehend change dynamics, paving the way for more informed decision-making and robust social impact strategies​1​.

In the context of the "Code Empower Program" from the Girls Code example, a Unique ID can be generated using non-personally identifiable information (non-PII). Here are a few methods:

  • CRM ID: If your organization uses a Customer Relationship Management (CRM) system, you can use the unique customer ID generated by the CRM.
  • Hashed Email: Hashing the participant's email address can create a unique identifier without revealing the email itself.
  • Phone Number Hash: Similarly, a hash of the participant's phone number.
  • These methods ensure each participant has a unique identifier while adhering to privacy standards by not using personally identifiable information directly.
  • Asking questions again, creates data collection fatigue.

Baseline Survey:

  • Demographics: Age, gender, education, etc.
  • Pre-existing Conditions or Behaviors: Initial conditions such as coding skills or awareness of trafficking risks.
  • Initial Knowledge or Attitudes: Understanding participants’ initial attitudes lays the groundwork for measuring change.
Question Question Type Best Practice Applied
What is your age? Closed-Ended Demographics
What is your gender? Closed-Ended Demographics
What is your highest level of education? Closed-Ended Demographics
Do you have any prior coding experience? Closed-Ended Pre-existing Conditions or Behaviors
What motivated you to join the Code Empower Program? Open-Ended Initial Knowledge or Attitudes

Exit Survey:

  • Changes in Behaviors or Conditions: Capturing alterations in behaviors or conditions is central to evaluating social impact.
  • Participant Satisfaction or Experience: Participant feedback provides invaluable insights.
  • Long-term Impact or Outcomes: Assessing long-term outcomes elucidates the enduring social impact.
Question Question Type Best Practice Applied
Have you noticed a change in your coding abilities? If so, please describe. Open-Ended Changes in Behaviors or Conditions
On a scale from 1-10, how satisfied are you with the Code Empower Program? Closed-Ended Participant Satisfaction or Experience
Do you feel the skills acquired will help you in your future endeavors? Please explain. Open-Ended Long-term Impact or Outcomes
Do you have any prior coding experience? Closed-Ended Pre-existing Conditions or Behaviors
What motivated you to join the Code Empower Program? Open-Ended Initial Knowledge or Attitudes

Info icon
POWERUP: Learn how to design effective impact learning and reporting. View tutorial
Search icon

Looking for something else?

Search our extensive library to find the answers or topics you're looking for.
Email icon

Still need help?

Can't find what you're looking for? Reach out for personalized assistance.
Contact support