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Questions and Answers
What will change the appearance of a histogram?
What will change the appearance of a histogram?
Changing the width of the intervals.
What type of plot is recommended for graphically displaying exam scores for 18 students ranging from 45% to 100%?
What type of plot is recommended for graphically displaying exam scores for 18 students ranging from 45% to 100%?
A stem & leaf plot.
Which one of the following variables is categorical?
Which one of the following variables is categorical?
- Type of cell phone service (correct)
- Height
- Age
- Weight
Which of the following variables is quantitative?
Which of the following variables is quantitative?
Which of the following is NOT a measure of center of the data?
Which of the following is NOT a measure of center of the data?
When the data are arranged in ascending numerical order, the median is the value which
When the data are arranged in ascending numerical order, the median is the value which
What does the five-number summary consist of?
What does the five-number summary consist of?
The standard Normal table can be used to find approximate percentages for any distribution that
The standard Normal table can be used to find approximate percentages for any distribution that
What can be concluded from the study about herbal tea?
What can be concluded from the study about herbal tea?
If Joe's IQ score is 133, how many standard deviations is it above the mean (mean = 100, standard deviation = 15)?
If Joe's IQ score is 133, how many standard deviations is it above the mean (mean = 100, standard deviation = 15)?
What percentage of IQ scores are more than 2.5 standard deviations above the mean?
What percentage of IQ scores are more than 2.5 standard deviations above the mean?
If the distribution of data is symmetric, then mean of the data _____ the median.
If the distribution of data is symmetric, then mean of the data _____ the median.
What does standard deviation measure?
What does standard deviation measure?
What is the difference between o- and s?
What is the difference between o- and s?
To standardize means to
To standardize means to
Which one of the following is NOT affected by outliers?
Which one of the following is NOT affected by outliers?
What symbol should be used to represent the mean of 24 minutes?
What symbol should be used to represent the mean of 24 minutes?
What is the range for the middle 99.7% of the values of the normal curve?
What is the range for the middle 99.7% of the values of the normal curve?
What percentage of produced corks do NOT meet specifications if the mean is 3 cm and standard deviation is 0.1 cm?
What percentage of produced corks do NOT meet specifications if the mean is 3 cm and standard deviation is 0.1 cm?
Below what diameter are the smallest 10% of the corks?
Below what diameter are the smallest 10% of the corks?
How many standard deviations is a cork with a diameter of 3.135 cm above the mean?
How many standard deviations is a cork with a diameter of 3.135 cm above the mean?
Which one of the following does NOT have the same units of measure as the data?
Which one of the following does NOT have the same units of measure as the data?
Why do we randomize in experiments?
Why do we randomize in experiments?
What type of study is conducted when measuring sulfate levels and distance from a steel plant?
What type of study is conducted when measuring sulfate levels and distance from a steel plant?
What type of bias occurs when many selected individuals refuse to answer questions in a stratified sample?
What type of bias occurs when many selected individuals refuse to answer questions in a stratified sample?
Two variables are confounded when
Two variables are confounded when
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Study Notes
Histogram Appearance
- Changing the interval width alters the appearance of a histogram.
Data Representation
- A stem-and-leaf plot is suitable for displaying exam scores of 18 students ranging from 45% to 100%.
Variable Types
- Categorical variables include types of cell phone service.
- Quantitative variables can be exemplified by weight.
Measures of Center
- Interquartile range is not a measure of central tendency, unlike median and mean.
Median Definition
- The median divides ordered data into two equal halves.
Five-Number Summary
- Comprises minimum, first quartile (Q1), median, third quartile (Q3), and maximum.
Standard Normal Table
- Useful for finding percentages in any distribution approximating a normal distribution.
Herbal Tea Study
- The effectiveness of herbal tea cannot be conclusively determined due to the influence of visits on results.
IQ Test Scores
- With a mean of 100 and a standard deviation of 15, a score of 133 is 2.2 standard deviations above the mean.
- Only 0.6% of scores exceed 2.5 standard deviations above the mean.
Symmetric Distribution
- In symmetric data distributions, the mean equals the median.
Standard Deviation Purpose
- Measures the variation of observations around the mean.
Population vs. Sample Standard Deviation
- Population standard deviation (σ) differs from sample standard deviation (s); both measure data variability.
Standardization Process
- Involves adjusting a value by subtracting the mean and dividing by the standard deviation.
Outlier Influence
- The median remains unaffected by outliers, in contrast to other measures.
Distribution of Test Completion Time
- College freshmen’s test completion time has a mean of 24 minutes, represented by μ.
Range for Normal Curve Values
- The range encompassing the middle 99.7% of normal curve values is 30.
Cork Manufacturing Specifications
- Corks’ diameters are normally distributed with a mean of 3 cm and standard deviation of 0.1 cm; 31.74% do not meet specifications.
Diameter Percentiles
- The smallest 10% of corks have diameters below 2.872 cm.
Standard Deviations Above Mean
- A cork with a diameter of 3.135 cm is 12 standard deviations above the mean.
Measurement Consistency
- A z-score does not share units of measure with the original data.
Randomization in Experiments
- Randomization eliminates bias in experimental research.
Observational Study Definition
- Analyzed sulfate levels at selected locations around a steel plant to observe the effect of distance on levels represents an observational study.
Non-Response Bias
- When participants selected from a stratified sample refuse to respond, this results in non-response bias.
Confounded Variables
- Two variables are considered confounded when the effect of one cannot be separated from the effect of the other.
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