/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 22 The figure below plots the avera... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

The figure below plots the average brain weight in grams versus average body weight in kilograms for 96 species of mammals. \({ }^{12}\) There are many small mammals whose points overlap at the lower left. (a) The correlation between body weight and brain weight is \(r=0.86 .\) Explain what this value means. (b) What effect does the elephant have on the correlation? Justify your answer.

Short Answer

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(a) \( r = 0.86 \) shows a strong positive relationship between body and brain weight. (b) The elephant likely upholds this strong correlation by fitting the general pattern.

Step by step solution

01

Understanding Correlation

Correlation, denoted as \( r \), measures the strength and direction of a linear relationship between two variables. In this problem, \( r = 0.86 \) indicates a strong positive linear relationship between the body weight and brain weight of the mammal species. This means that species with greater body weight tend to have greater brain weight.
02

Considering the Outlier Impact

The elephant is significantly larger than most other mammals in both body and brain weight. To understand its effect, consider that outliers can strongly influence correlation. Its inclusion likely increases \( r \) due to its alignment with the trend, but if it deviates significantly from the line of best fit, it could decrease \( r \). However, given \( r = 0.86 \) is high, this suggests that the elephant either fits well with the general trend or affects it minimally.
03

Justifying the Elephant's Effect

Since the correlation is strong, the elephant likely supports the overall positive trend of the data. It enhances the correlation if it fits the linear pattern seen in other data points: meaning that, as larger mammals generally have larger brains, the elephant follows this rule. If it were an outlier deviating from this, its presence would reduce \( r \), indicating less linearity.

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Key Concepts

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

Outliers
Outliers are data points that significantly differ from other observations in a dataset. They can strongly impact statistical calculations such as correlation. In data analysis, outliers can arise from measurement errors, variability in the data, or indicate a novel observation. When analyzing mammal data related to brain and body weights, an outlier might be a species with exceptionally large or small weights that doesn't fit the general trend. It's crucial to identify outliers, as they can skew the analysis, making the results misleading. Considering the elephant in the dataset, its sizable body and brain weight could classify it as an outlier. However, whether it disrupts or supports the overall trend depends on its alignment with other data points. For instance, if the elephant shows consistency with the linear pattern of larger body weights corresponding to larger brain weights, it may not negatively impact the correlation.
Linear Relationship
A linear relationship involves a straight-line connection between two variables on a graph. It's often represented by an equation of a line, such as \( y = mx + b \), where \( m \) is the slope and \( b \) is the y-intercept. In a strong linear relationship, changes in one variable are consistently associated with changes in the other. In the context of mammals, a linear relationship between body weight and brain weight suggests that as one increases, so does the other, in a predictable fashion. The correlation coefficient, \( r = 0.86 \), suggests a strong positive linear relationship in the dataset. This means there is a reliable pattern where larger mammals tend to have larger brains. Such a relationship makes it easier to predict brain weight from body weight and vice versa.
Mammals
Mammals are a diverse class of animals characterized by warm-bloodedness, hair or fur, and typically, live birth. In scientific studies, mammals are often used to explore biological relationships due to their varied sizes and traits. Analyzing mammal species' brain and body weights provides insights into evolutionary traits and ecological adaptations. For example, the data on 96 species in the exercise help scientists understand how brain size correlates with body size across diverse mammal species. This analysis can uncover patterns that are influenced by various factors such as diet, habitat, and behaviors. By examining these biological relationships, researchers can draw conclusions about the evolutionary pressures that may have shaped mammalian brain development.
Data Analysis
Data analysis involves systematically applying statistical or logical techniques to describe and illustrate, condense and recap, and evaluate data. It is a valuable tool for uncovering patterns, correlations, and insights in data sets. In the case of mammal body and brain weights, data analysis helps in drawing conclusions about the relationship between these two variables. Commonly, it involves steps such as cleaning data, identifying trends, computing statistical measures like correlation, and interpreting results. During analysis, it is essential to consider potential outliers, as they can significantly affect calculations. For instance, the correlation of \( r = 0.86 \) would inform a strong positive relationship, yet outliers like an elephant could sway this value if they deviate from the established trend. Ultimately, data analysis in this scenario provides a clearer picture of the typical brain-body weight relationship across mammal species.

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Most popular questions from this chapter

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