章节大纲

  • 常规

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  • 识别分类数据中的关联

    Calculating Frequencies
    ::计算频率

    The lesson    used  two-way tables to display frequencies. This section will take this one step further and analyze those frequencies. The way that  you will do this is by relative frequencies. A relative frequency is a frequency compared to a total. This total can be a row total, a column total or the overall total. Look back to the 2014 Olympics data table that you created:
    ::课程用双向表格显示频率。 本节将更进一步, 并分析这些频率。 您这样做的方式是用相对频率。 相对频率是相对于总计的频率。 这个总计可以是行总计、 列总计或总计。 请看您创建的2014年奥运会数据表 :

    lesson content

    You  can use this table to compute various frequency percentages, which you will use to analyze the data. When comparing a cell to the column total, we call this the column relative frequency . When comparing a cell to the row total, we call this the row relative frequency.
    ::您可以使用此表格来计算各种频率百分比, 用来分析数据。 在比较单元格和列总数时, 我们称此为列相对频率。 在比较单元格和行总数时, 我们称此为行相对频率 。

     

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    48.1% of all medal winners from both countries were from the United States.
    ::两国所有获奖者48.1%来自美国。

    TRUE
    ::真实

    FALSE
    ::公平交易

     

     

    Associations
    ::协会协会协会

    By calculating the percentages in the data,  you can use them to look for associations. An association is a relationship where different groups are more likely to have higher frequencies. Scientists look for associations amount relative frequencies when testing the effectiveness of medicines on the human body. Scientists or doctors will group the patients in the two groups before the test: the medicine groups and the placebo group. The m edicine group receives the medicine. The placebo group is told they will receive the medicine and instead receives a placebo that is meant to look like the medicine but has no effect on the patient. The placebo group is meant to have no treatment so that the results can be compared with the patients who took medicine. After the test is complete, the results will either be classified as effective or not effective. Below is a two-way table that shows the result of a test performed to determine a medicine’s effectiveness.
    ::通过计算数据中的百分比,你可以使用它们来寻找协会。协会是一个不同群体更有可能拥有较高频率的关系。科学家在测试人体药物有效性时寻找协会的相对频率。科学家或医生将在测试前将病人分为两类:医药组和安慰剂组。医药组将获得药品。安慰剂组将被告知他们将获得药品,而是得到一种安慰剂,这种安慰剂组将看起来像药物,但不会对病人产生影响。安慰剂组将没有治疗,因此结果可以与服用药物的病人相比较。测试完成后,结果将被归类为有效或无效。下面是一张双向表格,显示为确定药物有效性而进行测试的结果。

    Use the interactive to see the relative frequencies for the columns of the given table .
    ::使用互动来查看给定表格列的相对频率。

     

    INTERACTIVE
    Associations
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    • Drag the slider to reveal the relative frequencies of the given table.
      ::拖动滑块以显示给定表格的相对频率。
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    A second test was performed to test the effectiveness of a different medicine. The results are shown in the table below.
    ::进行了第二次测试,以检验不同医学的功效,结果见下表。

    Use the interactive to write the column relative frequencies as percentages.
    ::使用交互方式将列相对频率写成百分比。

     

    INTERACTIVE
    Placebo Effectiveness
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    • Input the correct percentages in the bottom table.
      ::将正确百分比输入下表。
    • Values can be determined by using the top table.
      ::值可以通过使用上表来确定。
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    Making Predictions
    ::作出预测

    Relative frequencies can also be used to make predictions about data. Below is data from a study on the relationship between the age of women and hair length. The study classified the women into two groups: participants who are younger than 35 and participants who are 35 or older. The length of the participant's hair was classified as either long or short. Short hair is identified as above shoulder length, and long hair is identified as below shoulder length.
    ::相对频率也可以用来预测数据。以下是有关妇女年龄和头发长度之间关系的研究数据。该研究将妇女分为两类:35岁以下的参与者和35岁以上的参与者。参与者的头发长度分为长头发或短头发。短发被确定为肩长以上,长发被确定为肩长以下。

    Use the interactive to answer the questions.
    ::使用交互方式回答问题。

     

    INTERACTIVE
    Making Predictions
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    Fill in the table with the correct data about the women:
    ::在表格中填写有关妇女的正确数据:

    • Under 35 with short hair: 414
      ::35岁以下短发:414
    • 35 and up with short hair: 902
      ::35岁,加上短发:902
    • Under 35 with long hair: 650
      ::35岁以下长头发长发:650
    • 35 and up with long hair: 598
      ::35岁,长发:598

    Round each percent to the nearest tenth.
    ::每回合百分之十到最近的十分之一。

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       Summary
    ::摘要

    • Find the  relative frequency by dividing each  frequency by the total.
      ::通过将每个频率除以总计来查找相对频率。