### 统计代写|生物统计学作业代写Biostatistics代考|Displaying Proportions

statistics-lab™ 为您的留学生涯保驾护航 在代写生物统计学Biostatistics方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写生物统计学Biostatistics方面经验极为丰富，各种代写生物统计学Biostatistics相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

## 统计代写|生物统计学作业代写Biostatistics代考|Displaying Proportions

Perhaps the most effective and most convenient way of presenting data, especially discrete data, is through the use of graphs. Graphs convey the information, the general patterns in a set of data, at a single glance. Therefore, graphs are often easier to read than tables; the most informative graphs are simple and self-explanatory. Of course, to achieve that objective, graphs should be constructed carefully. Like tables, they should be clearly labeled and units of measurement and/or magnitude of quantities should be included. Remember that graphs must tell their own story; they should be complete in themselves and require little or no additional explanation.

Bar Charts Bar charts are a very popular type of graph used to display several proportions for quick comparison. In applications suitable for bar charts, there are several groups and we investigate one binary characteristic. In a bar chart, the various groups are represented along the horizontal axis; they may be arranged alphabetically, by the size of their proportions, or on some other rational basis. A vertical bar is drawn above each group such that the height of the bar is the proportion associated with that group. The bars should be of equal width and should be separated from one another so as not to imply continuity.

## 统计代写|生物统计学作业代写Biostatistics代考|Changes

Familiar examples of rates include their use to describe changes after a certain period of time. The change rate is defined by

In general, change rates could exceed $100 \%$. They are not proportions (a proportion is a number between 0 and 1 or between 0 and $100 \%$ ). Change rates are used primarily for description and are not involved in common statistical analyses.
Example 1.11 The following is a typical paragraph of a news report:
A total of 35,238 new AIDS cases was reported in 1989 by the Centers for Disease Control (CDC), compared to 32,196 reported during 1988. The $9 \%$ increase is the smallest since the spread of AIDS began in the early 1980s. For example, new AIDS cases were up $34 \%$ in 1988 and $60 \%$ in 1987. In 1989, 547 cases of AIDS transmissions from mothers to newborns were reported, up $17 \%$ from 1988 ; while females made up just 3971 of the 35,238 new cases reported in 1989 ; that was an increase of $11 \%$ over $1988 .$
In Example 1.11:

1. The change rate for new AIDS cases was calculated as
$$\frac{35,238-32,196}{32,196} \times 100=9.4 \%$$
(this was rounded down to the reported figure of $9 \%$ in the news report).
1. For the new AIDS cases transmitted from mothers to newborns, we have
$$17 \%=\frac{547-(1988 \text { cases })}{1988 \text { cases }} \times 100$$
\begin{aligned} 1988 \text { cases } &=\frac{547}{1.17} \ &=468 \end{aligned}
(a figure obtainable, as shown above, but usually not reported because of redundancy).

Similarly, the number of new AIDS cases for the year 1987 is calculated as follows:
$$34 \%=\frac{32,196-(1987 \text { total })}{1987 \text { total }} \times 100$$
or
\begin{aligned} 1987 \text { total } &=\frac{32,196}{1.34} \ &=24,027 \end{aligned}

1. Among the 1989 new AIDS cases, the proportion of females is
$$\frac{3971}{35,238}=0.113 \text { or } 11.3 \%$$
and the proportion of males is
$$\frac{35,238-3971}{35,238}=0.887 \text { or } 88.7 \%$$
The proportions of females and males add up to $1.0$ or $100 \%$.

## 统计代写|生物统计学作业代写Biostatistics代考|Measures of Morbidity and Mortality

The field of vital statistics makes use of some special applications of rates, three types of which are commonly mentioned: crude, specific, and adjusted (or standardized). Unlike change rates, these measures are proportions. Crude rates are computed for an entire large group or population; they disregard factors

such as age, gender, and race. Specific rates consider these differences among subgroups or categories of diseases. Adjusted or standardized rates are used to make valid summary comparisons between two or more groups possessing different age distributions.

The annual crude death rate is defined as the number of deaths in a calendar year divided by the population on July 1 of that year (which is usually an estimate); the quotient is often multiplied by 1000 or other suitable power of 10 , resulting in a number between 1 and 100 or between 1 and 1000 . For example, the 1980 population of California was $23,000,000$ (as estimated by July 1) and there were 190,237 deaths during 1980 , leading to
\begin{aligned} \text { crude death rate } &=\frac{190,247}{23,000,000} \times 1000 \ &=8.3 \text { deaths per } 1000 \text { persons per year } \end{aligned}
The age- and cause-specific death rates are defined similarly.
As for morbidity, the disease prevalence, as defined in Section 1.1, is a proportion used to describe the population at a certain point in time, whereas incidence is a rate used in connection with new cases:
$$\text { incidence rate }=\frac{\begin{array}{c} \text { number of persons who developed the disease } \ \text { over a defined period of time (a year, say) } \end{array}}{\begin{array}{c} \text { number of persons initially without the disease } \ \text { who were followed for the defined period of time } \end{array}}$$
In other words, the prevalence presents a snapshot of the population’s morbidity experience at a certain time point, whereas the incidence is aimed to investigate possible time trends. For example, the 35,238 new AIDS cases in Example $1.11$ and the national population without AIDS at the start of 1989 could be combined according to the formula above to yield an incidence of AIDS for the year.

## 统计代写|生物统计学作业代写Biostatistics代考|Changes

1989 年，疾病控制中心 (CDC) 报告了 35,238 例新的艾滋病病例，而 1988 年报告了 32,196 例。9%增幅是自 1980 年代初艾滋病开始传播以来的最小增幅。例如，新的艾滋病病例上升34%1988 年和60%1987 年。1989 年，报告了 547 例从母亲传染给新生儿的艾滋病病例。17%从 1988 年开始；而在 1989 年报告的 35,238 例新病例中，女性仅占 3971 例；那是增加11%超过1988.

1. 新艾滋病病例的变化率计算为
35,238−32,19632,196×100=9.4%
（这被四舍五入到报告的数字9%在新闻报道中）。
2. 对于从母亲传染给新生儿的新的艾滋病病例，我们有
17%=547−(1988 案例 )1988 案例 ×100
导致
1988 案例 =5471.17 =468
（如上图所示，但通常不报告，因为冗余）。

34%=32,196−(1987 全部的 )1987 全部的 ×100

1987 全部的 =32,1961.34 =24,027

1. 1989年新增艾滋病病例中，女性比例为
397135,238=0.113 或者 11.3%
并且男性的比例是
35,238−397135,238=0.887 或者 88.7%
女性和男性的比例加起来1.0或者100%.

## 统计代写|生物统计学作业代写Biostatistics代考|Measures of Morbidity and Mortality

粗死亡率 =190,24723,000,000×1000 =8.3 死亡人数 1000 每年人

发病率 = 患病人数   在规定的时间段内（比如一年）  最初没有患病的人数   在规定的时间段内被跟踪的人

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