5 Number Summary
What is the median of this data set?
{12, 23, 34, 45, 54, 56, 67, 78, 89, 98}
55
(54 + 56) / 2
= 110 / 2
= 55
What is the formula for finding a Z-score?
(X - μ) / σ
What are the two types of variables in a scatterplot?
Explanatory and response
Response is dependent, explanatory is independent
An "individual" is...
An object described by a set of data
What is the equation for finding the mean?
(ΣX) / N
Also written as: (sum of all data points)/(number of data points)
Given this 5 Number Summary, find the IQR
Min = 5
Q1 = 14
Median = 32
Q2 = 44
Max = 53
Bonus: Would 70 be considered a suspected outlier?
IQR = 30
No; 1.5xIQR = 45
44+45=89, 70 is less than 89, so not a suspected outlier
How do you use the z-score?
(Hint: Which side is it?)
Use Table A to get the proportion of data to the left of x
What two numbers is the correlation always going to be between?
Bonus: What do both extremes mean?
-1 and 1
-1 means it is a perfect negative correlation
1 means it is a perfect positive correlation
What is the difference between categorical and quantitative variables?
A categorical variable places an individual into a group (categorizes)
A quantitative variable uses numerical values to charaterize an individual
When will the online portion of the exam be available?
Thursday afternoon to Friday at midnight
How do you find the median if there is an even number of data points?
You find the average of the two middle numbers
In a normal distribution, what is the probability that a randomly selected data point falls within one standard deviation of the mean?
68%
(68, 95, 99.7% rule)
A regression line
A researcher wants to use education level to explain differences in income.
What is the explanatory variable? What is the response variable?
Explanatory: Education level
Response: Income
What are the attributes of a Normal distribution?
The median is a better measure of center than the mean when the data is
Skewed/has many outliers
What is the official name of the number you get out of Table A?
What is the single most important thing to remember about correlation in data sets?
CORRELATION DOES NOT IMPLY CAUSATION
When is the distinction between explanatory and response variables essential?
When creating a least-squares regression line
What are the three types of bias in a survey?
Nonresponse, undercoverage, poor wording, response (incorrect information)