Statistic: 2.2 Organizing Quantitative Data
In a distribution that's skewed left
the tail to the left of the peak is longer than the tail to the right of the peak.
Discrete Variable
A discrete variable is a quantitative variable that has either a finite number of possible values or a countable number of possible values
Open Ended
A table is open ended if the first class has no lower class limit or the last class has no uppper class limit.
Stem-and-leaf plots are particularly useful for large sets of data.
False because stem-and-leaf plots lose their usefulness when data sets are large or when they consist of a large range of values.
The _________________ is the difference between consecutive lower class limits.
class width
Continuous Variable
A continuous variable may take on every possible value between any two values.
Why shouldn't classes overlap when summarizing continuous data in a frequency or relative frequency distribution?
Classes shouldn't overlap so there is no confusion as to which class an observation belongs.
There is not one particular frequency distribution that is correct, but there are frequency distributions that are less desirable than others.
The statement is true. Any correctly constructed frequency distribution is valid. However, some choices for the categories or classes give more information about the shape of the distribution.
In a uniform distribution
The frequency of each value of the variable is evenly spread out across the values of the variable.
A researcher wanted to determine the number of televisions in households. He conducts a survey of 40 randomly selected households and obtains the data in the accompanying table. Complete parts (a) through (h) below. (a) Are these data discrete or continuous? Explain.
The given data are discrete because they can only have whole number values.
In a bell-shaped distribution
The highest frequency occurs in the middle and frequencies tail off to the left and right of the middle.
In a distribution that's skewed right
The tail to the right of the peak is longer than the tail to the left of the peak.
The ______ class limit is the smallest value within the class and the ______ class limit is the largest value within the class.
lower - upper
Classes
are the categories by which data are grouped.
The least-squares regression line always travels through the point (x, y).
True
Discuss the advantages and disadvantages of histograms versus stem-and-leaf plots.
Stem-and-leaf plots are easier to make and can contain more information than histograms. However, they are not very useful for large data sets because they can be quickly constructed and can display both the individual data values and how they are grouped.
