Ch. 1
Histograms deal with ______ data, while bar graphs deal with ______ data.
Histograms deal with quantitative data, while bar graphs deal with categorical data.
Amy and Lily want to know how to find the z-score that corresponds to a particular percentile. They ask Kelly for help, who tells them to use the _________ function in their calculator.
Amy and Lily want to know how to find the z-score that corresponds to a particular percentile. They ask Kelly for help, who tells them to use the invNorm function in their calculator.
Correlation (r) measures the _______ and _______ of a linear relationship between two quantitative variables.
Correlation (r) measures the direction and strength of a linear relationship between two quantitative variables.
A "fake treatment" is also called a...
A "fake treatment" is also called a placebo.
We can describe the distribution of data as _________ when it has two distinct peaks.
We can describe the distribution of data as bimodal when it has two distinct peaks.
Eric proudly announced to everyone, “My doctor says my blood pressure is at the 90th percentile among men like me. That means I’m better off than about 90% of similar men.”
How should Eric's family interpret this result?
Eric proudly announced to everyone, “My doctor says my blood pressure is at the 90th percentile among men like me. That means I’m better off than about 90% of similar men.”
How should Eric's family interpret this result?
It's unhealthy to have blood pressure that's too high, so being at the 90th percentile means they should probably be concerned about his health.
The use of a regression line to pick the value of variables far outside the explanatory variables used to obtain the line is called...
The use of a regression line to pick the value of variables far outside the explanatory variables used to obtain the line is called...Extrapolation
An educator wants to compare the effectiveness of computer software for teaching Statistics with that of a textbook presentation. She gives a Statistics pretest to each of a group of high school juniors, then randomly divides them into two groups. One group uses the computer, and the other studies the text. At the end of the year, she tests all the students again and compares the increase in Statistics test scores in the two groups. Is this an observational study or an experiment? Justify your answer.
Experiment (students were randomly assigned to different teaching methods)
Explain why pictographs are bad.
Explain why pictographs are bad.
The size of the picture usually changes at a rate that's disproportional (and therefore non-representative) of the size of the quantity change it's intended to represent.
Star scores 680 on the SAT Mathematics test. The distribution of SAT scores is symmetric and single-peaked, with mean 500 and SD 100. Nancy takes the ACT Mathematics test and scores 27. ACT scores also follow a symmetric, single-peaked distribution—but with mean 18 and SD 6. Find the standardized scores for both students. Assuming that both tests measure the same kind of ability, who has the higher score?
Star's z-score (1.8) is higher than Nancy's (1.5). So Star has the higher score.
When a LSRL is made, it minimizes the....
When a LSRL is made, it minimizes the sum of the squared residuals (for y variable)
A common form of blocking used for comparing two similar treatments
A common form of blocking used for comparing two similar treatments
matched pairs design
Kevin is concerned about Miles' homework, so during each class he asks his AP Statistics teacher if Miles' homework was submitted the previous night. After many weeks of recording the answers (yes/no), he makes a table that shows what % of the time Miles did his homework for each day of the week. What type of table did Kevin create? (Table only includes % HW done for each day of the week) Be Specific
One-way relative frequency table
A company makes lids for drinks at fast food restaurants. The diameter in inches of their lids follows a ~N(3.98, 0.02) distribution. Suppose a restaurant requires drinks with lids between 3.95 and 4.05 inches.
a) What % of the lids will be too small to fit?
b) What % of the lids will be too large to fit?
A company makes lids for drinks at fast food restaurants. The diameter in inches of their lids follows a ~N(3.98, 0.02) distribution. Suppose a restaurant requires drinks with lids between 3.95 and 4.05 inches.
a) What % of the lids will be too small to fit?
~6.7%
b) What % of the lids will be too large to fit?
0.0002 -> about 0%
Two teachers are asked to judge students' presentations. Mike was curious about their methodology, so he analyzed the scores and found that one teacher scored students 20% lower than the other teacher. However, he also found a correlation coefficient of r=0.9 between the two teachers' scores. Is there a problem with Mike's analysis? Explain why or why not.
Two teachers are asked to judge students' presentations. Mike was curious about their methodology, so he analyzed the scores and found that one teacher scored students 20% lower than the other teacher. However, he also found a correlation coefficient of r=0.9 between the two teachers' scores. Is there a problem with Mike's analysis? Explain why or why not.
Not contradictory. r=0.9 means that one teacher consistently gave ~20% lower scores for each presentation.
Explain the difference between the types of inference that can be made from an observational study vs. an experiment? (explain each type of inference and their requirements)
Explain the difference between the types of inference that can be made from an observational study vs. an experiment? (explain each type of inference and their requirements)
Inference about a population: random selection (possible in both experiments and observational studies).
Inference about Cause & Effect: random assignment of treatments (only possible with experiments).