Vocabulary
Define Convenience Sampling
Choosing a sample based on how easy it is to find the data.
Draw a scatter plot that has a Pearson's moment correlation coefficient value of 0.
Graph limits:
0 < y < 10
0 < x < 10
The points should have no linear pattern, random placement.
The entire group you want to study in a statistical investigation
Population
Define Bias
An intentional or unintentional flaw in the design of a data collection method that causes the method to consistently give a value that either overestimates or underestimates the actual value for the entire population, resulting in over- or under-representation of certain portions of a population
A student records the number of fish in 10 different tanks: 5, 9, 3, 3, 17, 33, 2, 8, 10, 10
Find the Mean & Median
Mean: 10
Median: 8.5
A limitation of using Pearson’s correlation coefficient
It only measures linear relationships
Define Systematic Sampling
A method where you select data at regular intervals from an ordered list
Draw a scatter plot that has a Pearson's moment correlation coefficient value of -0.5.
Graph limits:
0 < y < 10
0 < x < 10
The points should have a linear pattern, with the highest y values on the left side.
A visual display that uses bars to represent frequency for continuous data
Histogram
Distinguish Discrete vs Continuous data
Discrete data is data that can be counted
Continuous data is data that is measured
A data set has a mean of 20 and a standard deviation of 4. Every value is transformed using x --> 3x-2. What is the new standard deviation?
12
A sampling method that ensures specific numbers from different groups are selected, but not randomly
Quota Sampling
Distinguish Interpolation vs Extrapolation & which is more reliable
Interpolation: estimates unknown values between known data points
Extrapolation: estimates values beyond the known range
Interpolation = more reliable
What are the expressions for finding upper and lower outliers?
Upper:
Q3+1.5(IQR)
Lower:
Q1-1.5(IQR)
Why is stratified sampling often more reliable than simple random sampling?
It ensures all subgroups are represented proportionally