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WGU C955 Formulas and Terms (Latest 2026/2027 Update) Applied Probability and Statistics | Questions and Verified Answers| 100% Correct
WGU C955 Formulas and Terms (Latest
2026/2027 Update) Applied Probability and
Statistics | Questions and Verified Answers|
100% Correct
Q: Simpsons Paradox
Answer:
A counterintuitive situation that occurs when a result that appears in individual groups of data
disappears or reverses when the groups are combined.
Can only occur when the sizes of the groups are inconsistent
Q: Lurking Variables :
Answer:
• A lurking variable is a variable not included in the study, but affects the variables that were
included in the study• Never assume that a causation exists just because there is an association
between two variables - always be on the lookout for lurking variables
Q: Causation
Answer:
A change in one variable creates a change in the other variable.o
Can only be determined from an experiment
Q: Association
Answer:
means there is a relationship between two variables.Association does not necessarily imply
causation.
o We can use scatterplots to visualize the data and determine if there is at least an association, but
we cannot determine causation from a scatterplot alone.o
Can establish association through an observational study.
Q: Observational Study
Answer:
There are no treatment or control groups because the participants self-select their groups.
Researchers observe if there is an association between variables.
Q: Experimental Study
Answer:
- Researchers randomly assign participants to two or more groups. One group is designated as a
control group where no treatment (placebo) is given while all other groups are given treatments
to determine if there is causation between variables.
Q: Graphical Displays:
Answer:
Just C - Pie chart or bar chart• Just Q - Histogram, stem plot, boxplot, or dot plot•
C ’ C - Two-way table with Conditional Percentages•
C ’ Q - Side-by-side boxplot with 5-number summary• Q ’ Q - Scatterplot with correlation
coefficient
Q: Correlation Coefficient (Q ’ Q)
Answer:
Strength: On a scatterplot, the closer the points are laid out in a line,the stronger the correlation.
measures the direction and strength of the linear relationship between the variables The closer r
is to +1, the stronger the positive correlation. The closer r is to -1, the stronger the negative
correlation. The closer r is to 0, the weaker the correlation.
Q: Positive Correlation
Answer:
scatterplot reveals an "uphill trend." as the explanatory variable increases, the response variable
increases.
Q: Negative Correlation
Answer:
scatterplot reveals a "downhill trend."As the explanatory variable increases, the response
variable decreases.
Q: No CorrelationAnswer:
scatterplot reveals no trend between the variables
Q: Variable Type Q ’ Q
Answer:
Graphical Display: Scatterplot
Numerical Measure: Correlation Coefficient (r value)
Q: Variable Type C ’ Q
Answer:
Graphical Display: Side by Side Boxplots
Numerical Measure: Five Number Summary
Q: Variable Type C ’ C
Answer:
Graphical Display: Two Way Table
Numerical Measure: Conditional Percentages
Q: Explanatory Variable
Answer:
Influences the response variable.
Q: Response Variable
Answer:
Is affected by the explanatory variable.
Q: Standard Deviation Rule
Answer:
68% of the data is within 1 standard deviation of the mean.•
95% of the data is within 2 standard deviations of the mean.•
99.7% of the data is within 3 standard deviations of the mean
Q: Mode -
Answer:
value that occurs most often in a data set
Q: Median
Answer:
halfway point, equal number of data points above the median as below, always order the data
from smallest to largest first
Q: Mean
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