1Normal distribution is also called?
Gaussian Distribution”; bell-shaped curve
2Continuous probability distribution that describes data that clusters around a mean
normal distribution
3normal distribution was developed by?
Abraham de Moivre
4who discovered the paper about normal distribution?
Karl Pearson
5used the normal curve to analyze astronomical data
Carl Friedrich Gauss
6when did Carl Friedrich Gauss use the normal curve to analyze astronomical data?
1809
7what are the properties of a normal distribution?
The distribution is bell-shaped.
• The mean, median, and mode is equal.
• It is unimodal
• It is symmetric about the mean.
• It is continuous.
• It is asymptotic.
• Total area: 100%
8The area under the part of a normal curve that lies within 1 standard deviation of the mean is about __%;
68
9The area under the part of a normal curve that lies within 2 standard deviation of the mean is about __%
95
10The area under the part of a normal curve that lies within 3 standard deviation of the mean is about __%
99.7
11Curves are generally classified as?
symmetrical or skewed
12Measures the deviation of a random variable’s given distribution from the normal distribution, which is symmetrical on both sides
Skewness
13A given distribution can be either be skewed to the left or the right
14A given distribution is shifted to the left with its tail on
the right side
Positively skewed distribution
15When a curve is __ skewed, most of the scores occur at the lower values of the horizontal axis and the curve tails off toward the higher end
positively
16A given distribution is shifted to the right with its tail on
the left side
Negatively skewed distribution
17When a curve is __ skewed, most of the scores occur at the higher values of the horizontal axis and the curve tails off toward the lower end
negatively
18Universally understood units in testing that allow test users to evaluate a person’s performance
in reference to other persons who took the same test.
Standard Scores
19The standard score indicates?
how many standard deviations an observation is above or below the mean
20what happens when you standardize a variable?
its mean becomes zero and its standard deviation
becomes one
21what are the two standard scores?
z-score and t-score
22Transformed score that designates how many standard deviation units the
corresponding raw score is above or below the mean
z-score
23Transformed score that always have a mean of 50 and a standard deviation of 10
t-score
25will show us the area percentages anywhere along
a standard normal distribution curve
z-scores
26area percentages are also called?
probabilities/proportions
27The area percentage (proportion, probability) calculated using a z-score will be a decimal value between __ and __, and will appear in a Z-Score Table
0 and 1
28The total area under any normal curve is?
1 or 100%
29The area on either sides of the mean is?
0.5 or 50%