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NAEP scores In 2015 , eighth-grade math scores on the National Assessment of Educational Progress had a mean of 283.56 in Maryland compared to a mean of 284.37 in Connecticut (Source: http://nces.ed.gov/nationsreportcard/ naepdata/dataset.aspx). a. Identify the response variable and the explanatory variable. b. The means in Maryland were respectively \(274,284,285,\) 291 and 294 for people who reported the number of pages read in school and for homework, respectively as \(0-5,6-10,11-15,15-20\) and 20 or more. These means were 270,281,284,289 and 293 in Connecticut. Identify the third variable given here. Explain how it is possible for Maryland to have the higher mean for each class, yet for Connecticut to have the higher mean when the data are combined. (This is a case of Simpson's paradox for a quantitative response.)

Short Answer

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Response variable: eighth-grade math scores. Explanatory variable: location (state). Third variable: number of pages read.

Step by step solution

01

Identify the Response and Explanatory Variables

The response variable is the outcome we are interested in measuring, which in this context, is the eighth-grade math scores on the NAEP. The explanatory variable is the factor that may influence or predict the response variable, which in this case, is the location (either Maryland or Connecticut).
02

Identify the Third Variable

The third variable in the context of this problem is the number of pages read in school and for homework, categorized into intervals: 0-5, 6-10, 11-15, 15-20, and 20 or more pages. This variable breaks the dataset into further subcategories.
03

Explain Simpson's Paradox Scenario

Simpson's paradox occurs when trends appear in different groups of data but disappear or reverse when the groups are combined. Here, despite Maryland having higher average scores within each reading category, Connecticut has a higher overall mean. This can occur if a higher proportion of students in Connecticut are in categories with higher scores (such as reading more pages) compared to Maryland. The distribution of students across these categories could thus lead to Connecticut having a higher total mean despite having lower means within each category.

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Key Concepts

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

Response Variable
In statistics, the response variable is also known as the dependent variable. It represents the outcome we are interested in examining through our study or experiment. In simple terms, it is the variable that "responds" to changes in the other variable. For instance, if we are looking at an experiment to determine how the amount of study time affects test scores, the test score would be your response variable.

In the case of the NAEP scores mentioned in the problem, the response variable is specifically the eighth-grade math scores. These scores are what researchers want to measure and analyze in order to see how they are influenced by different factors. Generally, understanding what the response variable is, helps in clarifying what exactly the study aims to measure or predict.
Explanatory Variable
The explanatory variable, sometimes known as the independent variable, explains or predicts changes in the response variable. Think of it as the variable you believe might cause some change. It is what you manipulate or categorize to see how it impacts the response variable.

In this particular statistics problem, the location (Maryland vs. Connecticut) acts as the explanatory variable. Researchers are interested in seeing if and how the geographical location impacts the NAEP scores.

Imagine you're conducting an experiment where you want to see if different teaching techniques influence student performance. The technique used would be your explanatory variable, as it's the factor you think might cause any variations in test scores, which would be the response variable. Determining the explanatory variable is crucial to establishing the study's framework, as it dictates what comparisons and analyses are necessary to understand the phenomena being studied.
Simpson's Paradox
Simpson's Paradox is a fascinating statistical phenomenon that can lead to misleading interpretations if not properly considered. It occurs when a trend that appears in different groups of data vanishes or reverses when these groups are combined into a single dataset.

In our exercise, we have a situation where Maryland shows higher average NAEP scores within each reading category; however, when the data are combined, Connecticut ends up with a higher overall mean. This paradoxical situation can happen because of the distribution of students across different categories of the third variable. For instance, if Connecticut has a larger proportion of students who read more pages per week, this can skew the overall mean upward despite Maryland having higher averages in each sub-category.

This counterintuitive result teaches an important lesson: always dig deeper into the data structures and distributions.馃攳 Never accept aggregated statistics without understanding their underlying components. Being mindful of Simpson's Paradox allows researchers and data analysts to make more informed and correct conclusions that truly reflect the data's story.

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Most popular questions from this chapter

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