Draw and describe the characteristics of the normal curve. Include a description of the different types of distribution.
What will be an ideal response?
• Normal probability distributions (also referred to as normal curves) are theoretical distributions that exist in our imagination as perfect and symmetrical, and actually consist of a family of distributions that have the same general bell shape—high in the middle and tapering to the ends.
• The normal curve is a bell-shaped curve. The distribution is symmetrical, with scores more concentrated in the middle than at the tails.
• Most distributions of human traits would form a normal curve if we gathered data from the entire population.
• The normal probability distribution has a number of characteristics that are important for interpreting test scores.
o Most test scores cluster or fall near the middle of the distribution, forming what we refer to as the average or the central tendency. The farther to the right or left you move from the average, the fewer scores there are.
o Most people will score near the middle of the distribution, making the center of the distribution the highest point.
The curve can continue to infinity, and therefore the right and left tails of the curve will never touch the baseline.
o Approximately 34.1% of the population will score between the mean and 1 standard deviation (we explain this term later in this chapter) above the mean, and approximately 34.1% will score between the mean and 1 standard deviation below the mean. Approximately 13.6% of the population will score between 1 and 2 standard deviations above the mean, and approximately 13.6% will score between 1 and 2 standard deviations below the mean. Approximately 2.1% of the population ?will score between 2 and 3 standard deviations above the mean, and approximately 2.1% will score between 2 and 3 standard deviations below the mean. This curve will capture most of the scores in a population.
o The curve is convex at its highest point and changes to concave at 1 standard deviation above the mean and 1 standard deviation below the mean.
• Not all psychological measurements, however, yield normal or bell-shaped curves.
o Some are negatively skewed (there is one peak, with many high scores).
o Some are positively skewed (there is one peak, with many low scores).
o Some are sharply peaked (there is one peak, and most individuals have the same score).
o Some are bimodal (there are two distinct peaks, typically with many low scores and many high scores).
You might also like to view...
When testing is necessary in order to determine pathology,
a. projective tests such as the Rorschach should be used. b. it is better to over assess than under assess the pathology. c. tests that overpathologize, like the Rorschach, should be avoided. d. labels will only help to define the problem.
Your text discussed a classic study in which people were asked which cards they would need to turn over in order to find out whether a rule about the letters and numbers on the cards was true or false. What did the study show?
a. People rely too heavily on denying the consequent. b. People have difficulty understanding double negatives. c. People typically avoid trying to disproving their hypotheses. d. People overuse bottom-up processing.
Which of the following is NOT a key dimension of attributional thinking according to Weiner's model?
a. Internal cause c. Unstable cause b. Stable cause d. Task difficulty
When the diets of severely malnourished children improve, they __________
A) continue to undereat B) rarely have lasting damage C) rarely show catch-up growth D) tend to gain excessive weight