A frequency distribution contains the frequency of every value in the distribution.

The distribution of empirical data is called a frequency distribution and consists of a count of the number of occurences of each value.
false
true
true
false
false
A grouped frequency distributon should be used instead of a frequency distribution when the

false
false
distribution is bimodal.
false
distribution is skewed.
true
variable is continuous.
When a variable is truly continuous, each value will have a frequency of 1. Therefore, grouped frequency distributions are needed with continuous variables.
A symmetric distribution

false
false
has equal positive and negative skews.
In a symmetric distribution, the tails are equally long. However, the tails themselves are not skew. Skew is defined as the relative lengths of the tails. A distribution cannot have both negative and positive skew.
true
has no skew.
false
can have either positive or negative skew, but not both.
In a symmetric distribution, the tails extend equally in both directions. Therefore, there is no skew.
The following distribution has

false
true
a positive skew.
false
a negative skew.
false
no skew.
skew1.gif
The tail in the positive direction is longer than the tail in the negative direction, thus it has a positive skew.
The area under the curve of a probability distribution is

1
0.0
The area is 1 by definition, meaning that the probability that a score chosen at random will occur under the curve is 1.
A normal or bell-shaped distribution has its greatest probability density in its tails.

The distribution is higher and therefore denser in the middle of the distribution.
false
true
true
false
Which of the following distributions is symmetric?

false
true
A
false
B
false
C
true
D
symm.gif
A and D are symmetric, meaning if you folded them in the middle, the two sides would match perfectly. Distributions B and C have positive skew.