8 - Normal Distribution, Probability And Statistical Significance Flashcards
1
Q
Negatively skewed
A
Cloche à droite
2
Q
Positively skewed
A
Cloche à gauche
3
Q
Characteristics of normal distribution
A
- the distribution is bilaterally symmetrical and bell-shaped
- mean, median and mode coincide
- tails never reach x-axis
- range differs because STD differs
- Kurtosis = degree of peakedness
- skewness = 0 ; peakedness = 3
4
Q
Negative z score
A
Indicate that the value is below the mean
5
Q
Z score
A
Provide a standard unit of relative worth that enable us to compare across different distributions.
6
Q
Slew type transformation
A
Moderate: sqrd
Substantial: ln
Extreme 1/x
7
Q
Probability of value between STD
A
68,26% - 1SD
95% - 1,96SD
99% - 2,58SD
99,9% - 3SD
8
Q
Testing weather a distribution is normal methods
A
- calculate skewness and kurtosis
- QQ plot
- Kolmogotov-Smirnov and Shapiro-Will tests
9
Q
Probability
A
Numerical measure of the likeliness of an event.
In practice event are neither impossible nor absolutely certain
10
Q
Level of significance
A
Or alpha level is the o value that defines very unlikely events. Alpha is the probability of Type I error
