Posted on Categories:Business Statistics, 商业统计, 商科代写

A histogram can provide information about the distribution of a variable, but it can’t show any pattern over time. A time series variable is a quantitative variable that has been measured or recorded at regular intervals over time. Usually, we require that the intervals are equally spaced, although values recorded for successive business days (skipping weekends and holidays) are usually treated as equally spaced. Whenever we have time series data, it is a good idea to look for patterns by plotting the data in time order.

When a time series has no strong trend or change in variability we say that it is stationary. ${ }^{9}$ A histogram can provide a useful summary of a stationary series but generally misses what is really going on in a variable that changes over time.

When a distribution is skewed, it may not be appropriate to summarize the data simply with a center and spread, and it can be hard to decide whether the most extreme values are outliers or just part of the stretched-out tail. How can we say anything useful about such data? The secret is to apply a simple function to each data value. One function that can change the shape of a distribution is the logarithm function. Let’s examine an example in which a set of data is severely skewed.

In 1980 , the average CEO made about 42 times the average worker’s salary. In the two decades that followed, CEO compensation soared when compared with the average worker’s pay. What does the distribution of a sample of 434 companies’ CEOs look like? Figure $3.16$ shows a histogram of the CEO compensation from a recent year.

These values are reported in millions of dollars. The boxplot indicates that some of the CEOs received extraordinarily high compensation. The reason that the histogram seems to leave so much of the area blank is that the largest observations are so far from the bulk of the data. This distribution is very skewed to the right.

## 商业统计代写

1980 年，CEO 的平均工资约为工人平均工资的 42 倍。在随后的二十年中，CEO 的薪酬与普通员工的薪酬相比飙升。434 家公司 CEO 样本的分布情况如何？数字3.16显示了最近一年 CEO 薪酬的直方图。

## MATLAB代写

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。