/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 3 A data set has values ranging fr... [FREE SOLUTION] | 91Ó°ÊÓ

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A data set has values ranging from a low of 10 to a high of \(50 .\) What's wrong with using the class limits \(10-20,20-30,30-40,40-50\) for a frequency table?

Short Answer

Expert verified
The class limits overlap at boundary points, causing some data to be counted twice.

Step by step solution

01

Understanding Class Limits

To determine if the class limits are appropriate, we first need to understand that class limits should cover each interval of the data set without leaving any gaps and without any overlap. In this problem, the proposed class limits are: \(10 - 20, 20 - 30, 30 - 40,\) and \(40 - 50\).
02

Identifying Overlapping Limits

Next, we check for overlap. Here, the endpoints of each class like \(20, 30,\) and \(40\) serve as the upper limit of one class and the lower limit of the next. This creates overlapping intervals, which can lead to counting some data points twice.
03

Identifying Gaps Between Classes

Even if the overlap issue were addressed, it would still be critical to ensure that there are no gaps between classes. In this case, since class limits are adjoining, there are no gaps, but the overlapping issue remains problematic.
04

Revising Class Limits

Class limits should be revised to avoid overlapping by adjusting the boundary points. A better range could be non-overlapping like \(10 - 19, 20 - 29, 30 - 39,\) and \(40 - 49\), or to ensure proper bins, consider \(10 - <20, 20 - <30, 30 - <40,\) and \(40 - <50\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Class Limits
Class limits are the boundary values that define each of the intervals in a frequency table. These boundaries split the entire range of data into smaller, manageable parts, making it easier to analyze and interpret the data.

When setting class limits, it is important to ensure that each data point falls into one class and only one class. Class limits should avoid overlap, as a single data point needs to clearly belong to one interval. For example, if you have a data set ranging from 10 to 50, well-defined class limits might be 10-19, 20-29, 30-39, and 40-49. This way, each class is distinct and a value like 20 would only belong to the 20-29 class, not the 10-20 class.

These boundaries also should ensure that there are no gaps between intervals so every data point fits into exactly one class without being missed. This requires careful selection of the upper and lower bounds for each class, ensuring continuity across the entire range of the data.
Data Intervals
Data intervals are fundamental segments in the analysis of any data set. Each interval, also known as a class, represents a specific range of values. When creating these intervals, there are some critical factors to take into account:
  • Interval Size: This should be consistent across all classes to avoid misrepresenting the distribution of data. Example: using 10-19, 20-29, 30-39, and 40-49 ensures equal interval size.
  • Number of Intervals: This depends on the range of data and how detailed you want your analysis to be. More intervals offer a finer analysis, while fewer intervals provide a broader overview.

Effective data intervals reveal the frequency of data occurrences in specified ranges. They simplify large data sets into meaningful patterns showing how data is distributed. Always select intervals that reflect the context and aim of your analysis.
Overlap in Data Sets
Overlap in data sets, particularly in the context of class limits and intervals, refers to a situation where a data point might belong to more than one class. This happens when the boundaries of intervals are not set correctly. For example, if intervals are defined as 10-20, 20-30, 30-40, and 40-50, a data point of 20 could fall into either the 10-20 or the 20-30 interval.

Overlap can lead to inaccuracies and skewed results in data analysis because it means some data points may be counted more than once. To avoid overlap, it is essential to adjust the class limits such that no boundary value is shared between consecutive intervals. An adjustment can be made by changing the class limits to something like 10-19, 20-29, 30-39, and 40-49.

Correctly setting boundaries not only avoids overlap but also ensures that all data is accounted for and allocated to a single group, maintaining the integrity of the data analysis. Avoiding overlap is fundamental for a clear and concise frequency distribution.

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Most popular questions from this chapter

Batting Averages The following data represent baseball batting averages for a random sample of National League players near the end of the baseball season. The data are from the baseball statistics section of the Denver Post $$\begin{aligned} &\begin{array}{cccccccc} 0.194 & 0.258 & 0.190 & 0.291 & 0.158 & 0.295 & 0.261 & 0.250 & 0.181 \end{array}\\\ &\begin{array}{cccccccc} 0.125 & 0.107 & 0.260 & 0.309 & 0.309 & 0.276 & 0.287 & 0.317 & 0.252 \end{array}\\\ &\begin{array}{ccccccc} 0.215 & 0.250 & 0.246 & 0.260 & 0.265 & 0.182 & 0.113 & 0.200 \end{array} \end{aligned}$$ (a) Multiply each data value by 1000 to "clear" the decimals. (b) Use the standard procedures of this section to make a frequency table and histogram with your whole-number data. Use five classes. (c) Divide class limits, class boundaries, and class midpoints by 1000 to get back to your original data.

How do college professors spend their time? The National Education Association Almanac of Higher Education gives the following average distribution of professional time allocation: teaching, \(51 \% ;\) research, \(16 \% ;\) professional growth, \(5 \% ;\) community service, \(11 \% ;\) service to the college, \(11 \%\); and consulting outside the college, \(6 \% .\) Make a pie chart showing the allocation of professional time for college professors.

The following data represent annual salaries, in thousands of dollars, for employees of a small company. Notice that the data have been sorted in increasing order. $$\begin{array}{ccccccccccccc} 54 & 55 & 55 & 57 & 57 & 59 & 60 & 65 & 65 & 65 & 66 & 68 & 68 \\ 69 & 69 & 70 & 70 & 70 & 75 & 75 & 75 & 75 & 77 & 82 & 82 & 82 \\ 88 & 89 & 89 & 91 & 91 & 97 & 98 & 98 & 98 & 280 & & \end{array}$$ (a) Make a histogram using the class boundaries 53.5,99.5,145.5,191.5 237.5,283.5 (b) Look at the last data value. Does it appear to be an outlier? Could this be the owner's salary? (c) Eliminate the high salary of 280 thousand dollars. Make a new histogram using the class boundaries \(53.5,62.5,71.5,80.5,89.5,98.5 .\) Does this histogram reflect the salary distribution of most of the employees better than the histogram in part (a)?

How does average height for boys change as boys get older? According to Physician's Handbook, the average heights at different ages are as follows: $$\begin{array}{|l|llllllll|} \hline \text { Age (years) } & 0.5 & 1 & 2 & 3 & 4 & 5 & 6 & 7 \\ \hline \text { Height (inches) } & 26 & 29 & 33 & 36 & 39 & 42 & 45 & 47 \\ \hline \end{array}$$ $$\begin{array}{l|ccccccc} \hline \text { Age (years) } & 8 & 9 & 10 & 11 & 12 & 13 & 14 \\ \hline \text { Height (inches) } & 50 & 52 & 54 & 56 & 58 & 60 & 62 \\ \hline \end{array}$$ Make a time-series graph for average height for ages 0.5 through 14 years.

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