For Problems 5–10, determine whether the graph can represent a normal curve. If it cannot, explain why.
Table of contents
- 1. Intro to Stats and Collecting Data1h 14m
- 2. Describing Data with Tables and Graphs1h 55m
- 3. Describing Data Numerically2h 5m
- 4. Probability2h 16m
- 5. Binomial Distribution & Discrete Random Variables3h 6m
- 6. Normal Distribution and Continuous Random Variables2h 11m
- 7. Sampling Distributions & Confidence Intervals: Mean3h 23m
- Sampling Distribution of the Sample Mean and Central Limit Theorem19m
- Distribution of Sample Mean - Excel23m
- Introduction to Confidence Intervals15m
- Confidence Intervals for Population Mean1h 18m
- Determining the Minimum Sample Size Required12m
- Finding Probabilities and T Critical Values - Excel28m
- Confidence Intervals for Population Means - Excel25m
- 8. Sampling Distributions & Confidence Intervals: Proportion1h 25m
- 9. Hypothesis Testing for One Sample3h 29m
- 10. Hypothesis Testing for Two Samples4h 50m
- Two Proportions1h 13m
- Two Proportions Hypothesis Test - Excel28m
- Two Means - Unknown, Unequal Variance1h 3m
- Two Means - Unknown Variances Hypothesis Test - Excel12m
- Two Means - Unknown, Equal Variance15m
- Two Means - Unknown, Equal Variances Hypothesis Test - Excel9m
- Two Means - Known Variance12m
- Two Means - Sigma Known Hypothesis Test - Excel21m
- Two Means - Matched Pairs (Dependent Samples)42m
- Matched Pairs Hypothesis Test - Excel12m
- 11. Correlation1h 24m
- 12. Regression1h 50m
- 13. Chi-Square Tests & Goodness of Fit2h 21m
- 14. ANOVA1h 57m
6. Normal Distribution and Continuous Random Variables
Standard Normal Distribution
Problem 8.1.29a
Textbook Question
Watching Television The amount of time Americans spend watching television is closely monitored by firms such as AC Nielsen because this helps determine advertising pricing for commercials.
a. Do you think the variable “weekly time spent watching television” would be normally distributed? If not, what shape would you expect the variable to have?
Verified step by step guidance1
Understand the variable: The variable "weekly time spent watching television" measures the amount of time people spend watching TV each week, which is a continuous quantitative variable.
Consider the nature of the data: Since time spent watching TV cannot be negative and some people might watch very little or no TV while others watch a lot, the distribution is unlikely to be symmetric.
Think about the shape of the distribution: Because many people might watch a moderate amount of TV and fewer people watch very high amounts, the distribution is expected to be skewed rather than normal.
Identify the type of skewness: Typically, this variable would have a right (positive) skew, meaning the tail on the right side (higher values) is longer or fatter than the left side.
Summarize the expectation: Therefore, the distribution of weekly time spent watching television is not expected to be normal but rather right-skewed, reflecting that most people watch moderate amounts and fewer watch very high amounts.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Normal Distribution
The normal distribution is a symmetric, bell-shaped curve where most data points cluster around the mean. It is important to understand if a variable follows this pattern because many statistical methods assume normality for accurate inference.
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Finding Z-Scores for Non-Standard Normal Variables
Skewness and Distribution Shape
Skewness describes the asymmetry of a data distribution. If data are not normally distributed, they may be skewed right (long tail on the right) or left (long tail on the left), indicating that values are more spread out on one side of the mean.
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Sampling Distribution of Sample Mean
Real-World Data Characteristics
Variables like weekly TV watching time often have natural limits (e.g., zero minimum) and may cluster at low values with fewer high values, leading to a right-skewed distribution rather than a normal one. Understanding this helps in choosing appropriate analysis methods.
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Introduction to Collecting Data
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