Qualitative Observations vs Quantitative Observations

Qualitative observations: Identify or describe elements or properties such as color, shape (silhouette), comparative size, structure, order, pattern. Senses of the observer are used to detect qualities. They can be extremely subjective and others may 'see' the exact same thing or event differently. They are not based on numbers but use qualitative measurement to make sense of behavior.

Quantitative observations are measurements: They use numerical measurements such as duration, height, number of repetitions, percentages, rate, frequency, speed, size, and other objective ways of recording dog behavior. Tools are often used to make measurements.   They are repeatable so that another person can use the same units and reproduce the observation (as in watching a video). They can be used to record change, make graphs and other visuals for ease of understanding and comparison etc.

Some observations may be both quantitative and qualitative, depending on the measuring tool or the person observing. For example. loudness. Qualitatively, a sound detector can rate the number of decibels a sound is. Qualitatively,  one person may observe that the same sound is louder than a friend who has a hearing impairment. Success is another example. How you define a successful step in training a dog may be different than another trainer. The key is to be clear on what your defined criteria are. Bias is inherent in both types.

From Wikipeida: "Qualitative methods produce information only on the particular cases studied, and any more general conclusions are only hypotheses.
Quantitative methods can be used to verify which of such hypotheses are true."