Chapter 2 Stats
How do you find lower class limits?
Find the lower limits, add the minimum value and the class width
After constructing a relative frequency distribution summarizing IQ scores of college students, what should be the sum of the relative frequencies?
If percentages are used, the sum should be 100%. If proportions are used, the sum should be 1
Why should the number of classes in a frequency distribution be between 5 and 20?
If the number of classes in a frequency distribution is not between 5 and 20, it may be difficult to detect any patterns.
How to find limits in a frequency distribution?
In a frequency distribution, each class has a lower class limit, which is the least number that can belong to the class, and an upper class limit, which is the greatest number that can belong to the class. Also, class boundaries are the numbers that separate classes without forming gaps between them. For data that are integers, subtract 0.5 from each lower limit to find the lower class boundaries. To find the upper class boundaries, add 0.5 to each upper limit.
In a frequency distribution, the class width is the distance between the lower or upper limits of consecutive classes
In a frequency distribution, the class width is the distance between the lower or upper limits of consecutive classes.
How do you find the upper limits?
Is 1 minus the lower limit
How are relative frequency displayed?
Relative frequency of a class is the percentage of the data that falls in that class. This is displayed by either a relative frequency histogram or a frequency polygon,
What is the difference between relative frequency and cumulative frequency?
Relative frequency of a class is the percentage of the data that falls in that class, while cumulative frequency of a class is the sum of the frequencies of that class and all previous classes.A frequency histogram will be the same as a relative frequency histogram, except the values on the vertical axis will be different.
How do you find class width?
The difference between the upper and lower class boundaries divided by the number of classes then round up to the next whole number.
What is a midpoint?
The midpoint of a class is the sum of its lower and upper limits divided by two.
What do ogive graphs measure and display?
Cumulative frequency of a class is the sum of the frequencies of that class and all previous classes. Since an ogive is a cumulative frequency graph, this is what it displays.
What is the difference between class limits and class boundaries?
Class limits are the least and greatest numbers that can belong to the class. Class boundaries are the numbers that separate classes without forming gaps between them. For integer data, the corresponding class limits and class boundaries differ by 0.5.
What is a frequency distribution table?
A frequency distribution is a table that shows classes or intervals of data entries with a count of the number of entries in each class.
What is the difference between a frequency polygon and an ogive?
A frequency polygon displays class frequencies while an ogive displays cumulative frequencies. These two graphs display the data differently, so it is useful to graph both when trying to find patterns in a data set.
What are some benefits of using graphs of frequency distributions?
By graphing a frequency distribution, it becomes easier to see where the observations are concentrated, making patterns easier to determine.
How do you find the range?
minimum minus the maximum
What are some benefits of representing data sets using frequency distributions?
By organizing data into a frequency distribution, it becomes easier to see where the observations are concentrated, making patterns easier to determine.
True or false: Class boundaries ensure that consecutive bars of a histogram touch.
True: Because consecutive bars of a histogram must touch, bars must begin and end at class boundaries instead of class limits. Class boundaries are the numbers that separate classes without forming gaps between them.