Observation equips us with the material for thought, reflection and judgment. Observers exposed to the same sense impressions do not necessarily see, hear, feel, taste or smell the same things. Observation is influenced by experience, knowledge and emotion. Attention plays an important part in observation. One can be trained to be a more effective observer.
Some people are more reliable witnesses than others.
The trained observer sees significant details. We draw inferences on the basis of observations, or on conclusions drawn from previous observations. Inference is the interpretation of facts. Valid inferences are based on sufficient and relevant evidence. Inferences express probability, not certainty.