Have you looked in a good dictionary? That's the thing to do when you need the definition of a word.
improbable = probably not going to happen
probable = likely to h appen
highly, equally should be easy.
As for the 2nd part, what do you think?
The tests can help us to know more accurately what to expect in terms of levels of performance or types of behavior of various individuals.
Their effectiveness is influenced by their objectivity, reliability, validity and the type of standardization group used.
Here is a portion of my lecture notes related to the above concepts;
Good tests require certain qualities.
I. Objectivity indicates consistency among scores, minimal scorer bias (r approaches +1 and is >. 90). Contrast with subjective measures (scoring reaction papers example).
II. Reliability indicates the consistency of scores when give to same individuals (r approaches +1 and is >.90). It requires good level of objectivity.
A. Test-retest indicates stability over time.
B. Equivalent/alternate form indicates consistency over various forms of the same test (psychology section tests example).
C. Split-half indicates consistency within a test (even-odd items example).
III. Validity means that a test "measures what it claims to measure." Although valid test needs to be reliable, reliability does not ensure validity (IQ vs. height, table with rubber yardstick examples). Valid if it correlates with criterion measure (ACT scores vs. grades example).
IV. Standardization involves two aspects.
A. Tests run with same procedures and conditions each time given (my tests example).
B. The above allows the use of norms (my tests, Dove test examples), comparison standards used to judge a specific score. Most tests use middle class, WASP norms (Problem?, explain).
Can classify tests into dichotomies — mutually exclusive either-or categories.
I. Group vs. individual tests. Individual can be given a group test, but group cannot be given individual test (explain). Individual tests costs more in terms of time and money, but they are more reliable (examples).
II. Verbal vs. performance (nonverbal, motor) . Performance tests minimize level required of ability in a specific language (triangle example). My tests are very verbal (explain).
III. Speed vs. power relates to time allowed to complete the task (explain). The "decline" of IQ with age may be related to this (terminal decline example).
IV. Achievement vs. Aptitude (p. 382) is not a true dichotomy, since the same test can supply both measures (predict, future RN examples). Intelligence is a general aptitude.
V. These dichotomies are independent of each other
You can expand on these factors. I hope this helps a little more. Thanks for asking.