1. What is ET50?

ET50 (Time at 50% response) is the time point at which 50% of the maximum response is achieved in time-response data. It is commonly used in pharmacological and biological studies to characterize response kinetics.

2. How Does the Calculator Work?

The calculator uses linear interpolation between data points to find the time at which the response reaches 50%:

Where:

• \( x_1, y_1 \) — Time and percent before 50% response
• \( x_2, y_2 \) — Time and percent after 50% response
• 50 — Target response percentage

Explanation: The calculator finds the two data points that bracket the 50% response level and calculates the exact time using linear interpolation.

3. Importance of ET50 Calculation

Details: ET50 provides a standardized measure to compare response kinetics across different conditions, treatments, or compounds. It is particularly useful in drug development, toxicology studies, and physiological research.

4. Using the Calculator

Tips: Enter time-response data pairs separated by commas, with each pair on a new line. Ensure data covers the 50% response point for accurate interpolation.

5. Frequently Asked Questions (FAQ)

Q1: What format should the data be in?
A: Enter time and percent values separated by commas, with each data point on a separate line (e.g., "0, 0" or "5, 25").

Q2: What if my data doesn't cross 50%?
A: The calculator requires data points that bracket the 50% level. If no data crosses 50%, ET50 cannot be calculated.

Q3: Can I use different response percentages?
A: This calculator specifically calculates ET50. For other percentages, the interpolation method would need to be adjusted.

Q4: How accurate is linear interpolation?
A: Linear interpolation provides good accuracy when data points are closely spaced. For non-linear responses, more complex interpolation may be needed.

Q5: What units should time be in?
A: Time can be in any consistent units (seconds, minutes, hours), but all data should use the same time units.