Questions and Answers
Is the statement '75% of the class plans to take another math class' an example of descriptive or inferential statistics?
What type of variable is 'eye color'?
Categorical
What is the process of coding in statistics?
The process of representing categorical variables with numbers.
What percentage of a class of 12 men and 25 women is male?
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How many men are there in a class of 271 students if 46.5% of them are men?
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What is the total number of students in a class with 15 women that is made up of 54% women?
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What information is missing that might contradict the claim that women prefer earlier statistics classes?
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Why are percentages or rates often better than counts for making comparisons?
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Is the study observing teenagers and adults choosing diet soft drinks observational or controlled?
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What type of study is it when boys are divided into two groups to compare violent actions after watching different types of cartoons?
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What is the response variable in a question about causality?
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Which method of data collection is suitable for making conclusions about causal relationships?
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What is an identifying mark of an observational study?
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What is the difference between two groups in an observational study that explains different outcomes called?
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What type of sample is obtained by dividing a population into homogeneous groups and selecting individuals from each group?
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A simple random sample is always preferred because it obtains the same information as other sampling plans but requires a smaller sample size.
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A frequency distribution lists the ________ of each category of data, while a relative frequency distribution lists the ________ of occurrences of each category of data.
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After constructing any relative frequency distribution, what should be the sum of the relative frequencies?
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What is it called when a distribution has most values relative small but also has a few very large values?
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What indicates the existence of multiple mounds in a distribution?
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What are values so large or so small that they do not fit into the pattern of the distribution called?
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What are two commonly used graphs to display the distribution of a sample of categorical data?
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What are Pareto charts?
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Which of the following is not a difference between bar charts and histograms?
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True or False? A bar chart is used for numerical variables while a histogram is used for categorical variables.
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When describing the distribution of a categorical variable, the category that appears most often is called the _____?
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A categorical variable is only called bimodal under what circumstances?
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What is the most common trick to mislead readers of bar graphs?
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For what type of distribution does the mean represent the typical value?
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What is statistics?
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What is the definition of a population in statistics?
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What is a sample?
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What does categorical describe in statistics?
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What does numerical describe in statistics?
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What is coded data?
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Give an example of using coded data.
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What is stacked data?
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What is unstacked data?
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What are two-way tables?
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What is a treatment variable?
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What is the outcome (response) variable?
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What is the objective of treatment vs. outcome variable analysis?
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What is a treatment group?
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What is a control group?
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What is the placebo effect?
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What is a controlled experiment?
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______ are a variable that has not been accounted for but which is causing a difference in the groups being studied.
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What are the three main components of a Numerical Distribution?
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Describe Histograms (3 things).
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According to the Empirical Rule, what percentage of observations will be within two standard deviations of the mean?
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What types of distributions does the Empirical Rule apply to?
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If an observation has a z-score of 0, which statement is true?
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Name two measures of the center of a distribution and state the conditions under which each is preferred for describing the typical value of a single data set.
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Under what conditions is the median preferred?
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Under what conditions is the mean preferred?
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When a distribution is skewed, the _____ is used to measure the center and the _____ is used to measure variation.
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Study Notes
Statistics Concepts
- Statistics involves collecting, organizing, summarizing, and analyzing data to make conclusions.
- Descriptive statistics summarize characteristics of a sample, while inferential statistics generalize findings from a sample to a larger population.
Types of Variables
- Categorical variables describe qualities or classes, such as "eye color".
- Numerical variables describe quantities or measurements and can be subjected to arithmetic operations.
Sampling Techniques
- A simple random sample is preferred for obtaining unbiased information but other methods may yield more cost-effective results.
- Stratified sampling divides the population into homogenous groups and selects randomly from each group to ensure representation.
Data Collection Methods
- Controlled experiments assign subjects to treatment groups, allowing for causal inferences.
- Observational studies record data without manipulating conditions, revealing correlations but not causations.
Data Representations
- Frequency distributions list data categories with counts, while relative frequency distributions show proportions relative to the total.
- Bar graphs illustrate categorical data, and pie charts represent proportions. Histograms display numerical distributions.
Distribution Characteristics
- Right-skewed distributions contain most values as small with a few large values, resulting in a longer tail on the right side.
- Outliers are extreme values that do not fit the overall distribution pattern, potentially distorting analysis.
Measures of Center
- The mode defines the most frequently occurring category in a dataset, while the mean and median serve as central tendency measures.
- The median is preferred for skewed data or datasets with outliers, whereas the mean is better for symmetric distributions.
Key Statistical Rules
- The Empirical Rule applies to symmetric, unimodal distributions, stating that approximately 95% of observations fall within two standard deviations from the mean.
Experimental Design
- Control groups do not receive the treatment, serving as a baseline for comparison.
- The placebo effect can occur when subjects respond to the belief that they are receiving treatment, even if they are not.
Confounding Variables
- These additional variables can skew results if not accounted for, leading to erroneous conclusions about relationships in observational studies.
Visualization Aids
- Histograms consist of consecutive bins that touch, with heights corresponding to counts of observations in each interval.
- Pareto charts sort data from most to least frequent, emphasizing the most impactful factors.
Understanding Statistical Terms
- A response variable measures outcomes in relation to treatment variables.
- Coded data utilizes numbers to represent categorical responses for easier analysis.
Summary of Key Points
- Use percentages for accurate group comparisons by accounting for size differences.
- In a bimodal distribution, two categories have nearly the same frequency.
- Statistical graphs should be designed to avoid misleading representations through scale manipulations or other tactics.
Studying That Suits You
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Description
Test your knowledge on statistics with these flashcards covering key concepts from the introductory course. This quiz focuses on understanding the difference between descriptive and inferential statistics through practical examples.