Answer to Question 1
Answer: Allport defined three different kinds of traits: Central traits are of major importance for an individual. Secondary traits are of lesser importance, less often noticeable. Some individuals have one trait that is seen very often and dominates their life. Such a trait is called a cardinal trait.
Answer to Question 2
Answer: Idiographic: The goal is to understand the personality of an individual. Techniques used include case studies and experiments using individuals. Nomothetic: The goal is to discover universal concepts and traits that can be applied across groups and cultures. Techniques include questionnaires that can be given to large groups of people and then analyzed statistically by such methods as factor analysis. Researchers such as Eysenck and Allport looked for organized sets of traits, tied to personality theory. Often their models are organized in hierarchies where types are subdivided into traits which are further subdivided.
Traits and trees
Derived traits
Scaling of Size to Other Traits.
Other Medelian Traits in Humans
Common Traits of Flowers
Sources of Variation in Traits Among Individuals of a Species