Normal distribution

Question 1

Skewness
- what does it measure?
- what does zero mean? Pos. Neg.?

Answer 1

• relative symmetry
• zero means perfect symmetry (the larger the value, the more asymmetrical)
• the tail (right = positive_

Question 2

Kurtosis
mesokurtic

Answer 2

• measures thickness (thin fat) of tails of the distribution (K = 3)

mesokurtic: normal bell-shape dist.

Question 3

Platykurtic
Leptokurtic

Answer 3

• flatter and shorter tails (K = less than 3)
• more peaked, longer tails (K = greater than 3)

Question 4

Normal Guassian curve
features

Answer 4

• unimodal
• symmetrical => 50% of the data is above and 50% is below the mean
• no skew

Question 5

What is the point of inflection?

Answer 5

• when the curve begins to turn more outwards
• 3 points of inflection generally (measured by 1SD from the mean)

Question 6

Standardized Normal Curve features

Answer 6

• simplest ND
• every normal distribution is a version of the SND
• theoretical curve (a model for comparison)
• mean = 0, therefore SD = 1
• to infinity (infi. no. of cases)

Question 7

Can you convert a normal distribution into the SND?

Answer 7

Yes!
- allows u to compare scores on dif. distributions w/ dif/ means and SDs
- find the probability of observations (values, cases) in a dist. falling above or below the mean