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A two-way table is shown for two groups, 1 and \(2,\) and two possible outcomes, A and B. In each case, (a) What proportion of all cases had Outcome \(\mathrm{A}\) ? (b) What proportion of all cases are in Group \(1 ?\) (c) What proportion of cases in Group 1 had Outcome \(\mathrm{B} ?\) (d) What proportion of cases who had Outcome \(\mathrm{A}\) were in Group \(2 ?\) $$\begin{array}{|l|cc|c|}\hline & \text { Outcome A } & \text { Outcome B } & \text { Total } \\ \hline \text { Group 1 } & 40 & 10 & 50 \\ \text { Group 2 } & 30 & 20 & 50 \\\\\hline \text { Total } & 70 & 30 & 100 \\\ \hline\end{array}$$

Short Answer

Expert verified
a) 70% b) 50% c) 20% d) Approximately 42.857%

Step by step solution

01

Proportion with Outcome A

There are a total of 70 cases with Outcome A. As the total number of cases is 100, the proportion of all cases that had Outcome A is \(\frac{70}{100} = 0.7\) or 70%.
02

Proportion in Group 1

There are a total of 50 cases in Group 1. Thus, the proportion of all cases that are in Group 1 is \(\frac{50}{100} = 0.5\) or 50%.
03

Proportion of cases in Group 1 with Outcome B

There are 10 cases in Group 1 with Outcome B. Thus, the proportion of cases in Group 1 that had Outcome B is \(\frac{10}{50} = 0.2\) or 20%.
04

Proportion of cases with Outcome A in Group 2

There are 30 cases with Outcome A in Group 2. Hence, the proportion of cases that had Outcome A and were in Group 2 is \(\frac{30}{70} = 0.42857\) approximately or 42.857%.

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Key Concepts

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

Proportion Calculation
Proportion calculation is a fundamental concept in statistics, especially when working with two-way tables. It involves finding the ratio of a specific outcome or group within the total sample size. Simply put, it shows us the part of the whole we are dealing with in percentage or fraction.
To calculate the proportion, use the formula \( \frac{\text{specific group count}}{\text{total count}} \). For example, in our exercise, when finding the proportion of all cases that resulted in Outcome A, you take the number of Outcome A cases (70) and divide by the total number of cases (100), giving \( \frac{70}{100} \), which simplifies to 0.7 or 70%.
Here’s a quick guide on when to use proportion calculations:
  • When you want to compare parts to the whole.
  • When determining odds or likelihoods within data sets.
  • When converting data to an easily understandable format like percentages.
Statistical Analysis
Statistical analysis allows us to draw conclusions about data sets, like those represented in a two-way table. When dealing with proportions, it helps us understand and interpret the significance of data groupings and outcomes.
In this context, statistical analysis often involves comparing calculated proportions to determine patterns or trends. For example, when analyzing the two-way table, calculating the proportions of people in Group 1 or 2 helps us understand group distribution within the given context.
It’s essential in statistical analysis to consider:
  • The total sample size, as small samples might not give a reliable representation.
  • Consistency in the data and how it’s recorded, ensuring accuracy in proportions.
  • Comparison between proportions to identify significant differences or similarities across groups.
Thus, statistical analysis transforms raw data into meaningful insights through careful evaluation of proportions.
Group Comparison
Understanding group comparison involves analyzing how different groups perform across certain criteria, like outcomes in a two-way table. In our exercise, we're comparing Group 1 and Group 2 concerning outcomes A and B.
With group comparisons, we can answer questions such as: how does the behavior or result of one group compare to another? Which group has a higher proportion regarding a specific outcome? For instance, with Outcome B, Group 1 has 10 cases, making the proportion of 0.2, whereas Group 2 has a higher number, showing different engagement.
Key elements in group comparison include:
  • Clear identification of the groups and what is being measured or compared.
  • Consistency in measurement to ensure fair comparison across groups.
  • Contextual understanding of the differences, meaning results should be viewed in light of what they represent beyond numbers.
By focusing on these aspects, group comparison not only highlights differences but also enhances understanding of data through visual and statistical evaluation.

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Most popular questions from this chapter

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