Variables
Takes a wide range of values and it is sensible to add, subtract, or take averages with those values.
What is a numerical variable?
Sampling method in which each case in the population has an equal chance of being included and there is no implied connection between the cases in the sample.
What is a simple random sample?
The percentage that fits the following question: "If Q1 = 8% and Q3 = 14%, what is the IQR?"
What is 6%?
Name two defining characteristics of a normal distribution.
What is symmetric, bell-shaped, centered around the mean, etc.?
Two events that cannot both happen together.
What is disjoint/mutually exclusive?
A variable that might causally affect another.
What is an explanatory variable?
Sampling method that matches the following example: A political survey is done by stopping people walking in the Bronx.
What is a convenience sample?
A data set in which the mean is less than the median.
What is skewed left?
Formula for finding the z-score of an observation.
What is z = (x-mu)/sd?
Number that answers the following question: "What is the probability of rolling a 1 or a 2 on a fair-sided die?"
What is 1/3?
A variable that is correlated with both the explanatory and response variables and causes an association when there is not one.
What is a confounding variable?
A statistics student who is curious about the relationship between the amount of time students spend on social networking sites and their performance at school decides to conduct a survey. He randomly samples 5 classes and asks a random sample of students from those classes to fill out the survey. What kind of sampling method is being used here?
What is multi-stage sampling?
Name the ways to measure center and spread that are resistant to outliers.
What is median and IQR?
Head lengths of brushtail possums follow a normal distribution with mean 92.6 mm and standard deviation 3.6 mm. Compute the Z-score for possums with head length of 95.4 mm.
What is 0.78?
Number that answers the following question: "If P(A) = 0.2, P(A and B) = 0.1, and P(A or B) = 0.4, what is P(B)?"
What is 0.3?
Number that answers the following question: "Suppose we have a random variable X that takes value 0, with probability 0.2, value 1 with probability 0.5, and value 2 with probability 0.3. What is the expected value of X?"
What is 1.1?
A city council has requested a household survey be conducted in a suburban area of their city. The area is broken into many distinct and unique neighborhoods, some including large homes, some with only apartments, and others a diverse mixture of housing structures. They decide to divide the city into 20 neighborhoods, and sample 10 households from each neighborhood. What sampling method is being used here.
What is stratified sampling?
The Buteyko method is a shallow breathing technique developed by Konstantin Buteyko, a Russian doctor, in 1952. Anecdotal evidence suggests that the Buteyko method can reduce asthma symptoms and improve quality of life. In a scientific study to determine the effectiveness of this method, researchers recruited 600 asthma patients aged 18-69 who relied on medication for asthma treatment. These patients were randomly split into two research groups: one practiced the Buteyko method and the other did not. Patients were scored on quality of life, activity, asthma symptoms, and medication reduction on a scale from 0 to 10. On average, the participants in the Buteyko group experienced a significant reduction in asthma symptoms and an improvement in quality of life. What are the variables in this study?
What is practiced method (or not), quality of life, activity, asthma symptoms, and medication reduction?
The average daily high temperature in June in LA is 77◦F with a standard deviation of 5◦F. Suppose that the temperatures in June closely follow a normal distribution. What is the probability of observing an 83◦F temperature or higher in LA during a randomly chosen day in June? (round to two decimal places)
What is 0.12?
Formula for the conditional probability of outcome A given condition B.
What is P(A|B) = P(A and B)/P(B)?
As car mileage increases, the price of the car goes down. What kind of association is being described here?
What is a negative association?
A city council has requested a household survey be conducted in a suburban area of their city. The area is broken into many distinct and unique neighborhoods, some including large homes, some with only apartments, and others a diverse mixture of housing structures. They decide to divide the city into 20 neighborhoods, randomly sample 3 neighborhoods, and then sample all households from those 3 neighborhoods. What sampling method is being used here?
What is cluster sampling?
Number the answers the following question: "Consider a contingency table with homeownership (rent/mortgage/own) in the first row and application type (individual/joint) being the first column. If the number of individuals who rent is 3496, the number of overall renters is 3858, and the number of total individuals is 8505, what is the row proportion for individual/rent?"
What is 3496/8505 = 0.411?
Based on a sample of 100 men, the heights of male adults in the US is nearly normal with mean 70.0” and standard deviation 3.3”. Erik’s height is at the 40th percentile. How tall is he? (round to two decimals)
What is 69.18 inches?
Number that answers the following question: "Consider flipping a fair coin, what is the probability that the first heads occurs on the third trial?"
What is 0.125?