Why are the averaged results in the Datalog Grid at the Measurement level different than the averaged results at the Acquisition level? - WKB319109
ENVIRONMENT
- Dynamics
- Dynapro
- NanoStar
- ZetaStar
- DYNAMICS software
- DLS instrument
ANSWER
The averaged results at the Measurement level in the Datalog Grid differ from those at the Acquisition level because of how the data is processed. In the Datalog Grid, auto-correlation functions (ACFs) from each acquisition are first averaged into one ACF and then fitted once. In contrast, the Acquisition-level averages are calculated by fitting each ACF individually and then averaging the results. This difference in methodology leads to different average values. For DLS data analysis, averaging ACFs before fitting is preferred to reduce noise and artifacts.
ADDITIONAL INFORMATION
<31>Why are the averaged results in the Datalog Grid at the Measurement level different than the averaged results at the Acquisition level?
In DYNAMICS, the average values for the acquisitions of a measurement conducted by a DLS instrument are displayed at the table below the acquisitions:
However, these values are not the same for the average results displayed for the measurement in the Datolog Grid (when you click measurements and go to datalog grid):
This is because the results displayed in the Measurements-Level of the Datalog Grid for each measurement are the result of the auto-correlation functions (ACFs) being averaged into one ACF and then fitted once. The average results shown within a measurement consist of ACFs individually being fit and the results displayed per row and averaged at the bottom. When analyzing DLS data, it is always most appropriate to average the ACFs first and then fit the data, to help reduce bad fits due to noise and minimize artifacts.