Definitions
e=y-(y-hat)
or e=observed-predicted
A residual that is negative
What is an overestimation?
a) What is the probability a randomly selected game is released on a home console.
703/912~0.77
Randomly select 100 students, each having the same chance of being selected.
Simple Random Sampling
A pie chart can be used with this type of data
Categorical
Researcher impose treatments and controls in this type of study
Experiment
A correlation coefficient of 0.75
What is a moderately strong, positive linear relationship.
c) What is the probability that a randomly selected game is released for a home console AND is not considered a role-playing game?
640/912~0.702
Combining multiple sampling methods.
Multi-stage sampling
A histogram can be used with this type of data
Quantitative
Researchers observe characteristics and take measurements in this type of study
Observational study
A coefficient of determination of 0.32
Approximately 32% of the variation in the response is explained by the regression model using the predictor.
d) What is the probability a randomly selected game is released on a handheld or is a role-playing game?
(63+31+178)/912~0.298
(94+209-31)/912~0.298
1-(640/912)~0.298
Every 15th student that enters the building in the morning is selected and asked.
Systematic Sampling
This type of plot should be used to display two quantitative variables
Scatterplot
Sensitivity
# of true positives / # of those with the condition (sick)
A y-intercept of 1.2
When x=0, the predicted mean y is 1.2
e) What is the probability a randomly selected game is a role-playing game, given that it is released on a handheld device?
31/209~0.148
Randomly sample 2 Homerooms from the list of all Homerooms. Ask all students in each room.
Cluster Sampling
This type of plot should be used to display two categorical variables
Comparative bar plot
Stacked bar plot
Specificity
# of true negatives / # of those who do NOT have the condition (healthy)
A slope value of -5.8
For every additional one unit increase in x, the predicted mean y will decrease by 5.8 units.
f) Are the events "Handheld" and "Role-Playing" independent?
No, NOT independent.
**Make sure you show your work with a mathematical argument**
Divide the student body into 2 groups, Males and Females. We will randomly sample 50 students from the Males, randomly sample 50 students from the Females.
Stratified Sampling
This type of plot should be used to display one quantitative and one categorical variables
Comparative boxplot
Comparative histogram
Comparative dotplot
Comparative stem-and-leaf plot