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# 数据科学代写|经济统计代写Economic Statistics代考|ECON205 Frequency Distribution

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## 数据科学代写|经济统计代写Economic Statistics代考|Frequency Distribution

We begin the discussion of how tabular and graphical displays can be used to summarize categorical data with the definition of a frequency distribution.
FREQUENCY DISTRIBUTION
A frequency distribution is a tabular summary of data showing the number (frequency) of observations in each of several nonoverlapping categories or classes.

Let us use the following example to demonstrate the construction and interpretation of a frequency distribution for categorical data. Coca-Cola, Diet Coke, Dr. Pepper, Pepsi, and Sprite are five popular soft drinks. Assume that the data in Table $2.1$ show the soft drink selected in a sample of 50 soft drink purchases.

To develop a frequency distribution for these data, we count the number of times each soft drink appears in Table 2.1. Coca-Cola appears 19 times, Diet Coke appears 8 times, Dr. Pepper appears 5 times, Pepsi appears 13 times, and Sprite appears 5 times. These counts are summarized in the frequency distribution in Table 2.2.

This frequency distribution provides a summary of how the 50 soft drink purchases are distributed across the five soft drinks. This summary offers more insight than the original data shown in Table $2.1$. Viewing the frequency distribution, we see that CocaCola is the leader, Pepsi is second, Diet Coke is third, and Sprite and Dr. Pepper are tied for fourth. The frequency distribution summarizes information about the popularity of the five soft drinks.

## 数据科学代写|经济统计代写Economic Statistics代考|Relative Frequency and Percent Frequency Distributions

A frequency distribution shows the number (frequency) of observations in each of several nonoverlapping classes. However, we are often interested in the proportion, or percentage, of observations in each class. The relative frequency of a class equals the fraction or proportion of observations belonging to a class. For a data set with $n$ observations, the relative frequency of each class can be determined as follows:
RELATIVE FREQUENCY
$$\text { Relative frequency of a class }=\frac{\text { Frequency of the class }}{n}$$
The percent frequency of a class is the relative frequency multiplied by 100 .
A relative frequency distribution gives a tabular summary of data showing the relative frequency for each class. A percent frequency distribution summarizes the percent frequency of the data for each class. Table $2.3$ shows a relative frequency distribution and a percent frequency distribution for the soft drink data. In Table $2.3$ we see that the relative frequency for Coca-Cola is $19 / 50=.38$, the relative frequency for Diet Coke is $8 / 50=.16$, and so on. From the percent frequency distribution, we see that $38 \%$ of the purchases were Coca-Cola, $16 \%$ of the purchases were Diet Coke, and so on. We can also note that $38 \%+26 \%+16 \%=80 \%$ of the purchases were for the top three soft drinks.

## 数据科学代写|经济统计代写ECONOMIC STATISTICS代 考|FREQUENCY DISTRIBUTION

50 份软饮料购买样本中选择的软饮料。

## 数据科学代写|经济统计代写ECONOMIC STATISTICS代 考|RELATIVE FREQUENCY AND PERCENT FREQUENCY DISTRIBUTIONS

Relative frequency of a class $=\frac{\text { Frequency of the class }}{n}$

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MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。