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 occurrences of each value. false true true false false A grouped frequency distribution 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/are 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.