WGU C955 Formulas and Terms (Latest 2023/ 2024 Update) Applied Probability and Statistics | Questions and Verified Answers| 100% Correct

WGU C955 Formulas and Terms (Latest

2023/ 2024 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