Best fit likelihood and MLE estimated parameters for the fastest and slowest cells.

The Gaussian distribution better fits tracks with mean speed > 15 μm/min while lognormal better fits tracks with mean speed < 5 μm/min. The step speed distribution for fast tracks has a shorter and lighter tail than the sample of tracks with slower mean speeds. Best negative loglikelihood scores are in bold. For tracks with mean speed of < 5 um/min, skew is 2.37 and kurtosis 13.3; for tracks with mean speed > 15 um/min, skew is 0.52 and kurtosis 3.98.