Scatterplots and Correlation
A scatterplot shows points trending upward from left to right. What is the direction of the association?
What is Positive Association
In a regression equation, what does the y-intercept represent?
What is the predicted value of y when x=0
A regression line has slope 2.42. Interpret this slope.
What is for every 1-unit increase in x, the predicted y increases by 2.4 units
When performing a hypothesis test for slope, what is the null hypothesis?
What is the population slope is zero (no linear relationship)
What does a 95% confidence interval for slope mean?
What is we are 95% confident the interval captures the true population slope
What statistic measures the strength and direction of a linear relationship?
What is Correlation Coefficient r
A residual is calculated using what formula?
What is residual=observed value−predicted value
What are the explanatory and response variables also called?
What is Dependent and Independent Variables
What does the alternative hypothesis claim in a regression significance test?
What is the population slope is not zero
If a confidence interval for slope includes 0, what conclusion can be made?
What is there is not convincing evidence of a linear relationship
If r=−0.92, how would you describe the relationship?
What is strong negative linear relationship
What does a residual plot help determine?
What is whether a linear model is appropriate
What does an outlier in a scatterplot mean?
What is a point that falls far from the overall pattern
What distribution is used for inference about slope?
What is a t-distribution
What happens to a confidence interval when the confidence level increases?
What is the interval becomes wider
True or False: Correlation proves causation.
What is False
If the residual plot shows a curved pattern, what does that suggest?
What is a linear model is not appropriate
What is an influential point?
What is a point that strongly affects the regression line
What condition states that observations must be independent?
What is the Independence Condition
Which value is used to calculate the margin of error for slope inference?
What is the critical t-value
What does it mean if r=0?
What is there is no linear relationship
A researcher creates a regression model to predict a person’s salary based on years of experience. The slope of the regression line is 3,200.
Interpret the slope in context.
What is for every additional year of experience, the predicted salary increases by 3,200 dollars.
True or False: Switching the explanatory and response variables changes the regression equation.
What is true
If the p-value is less than signifigance level, what decision do you make?
What is reject the null hypothesis
A confidence interval for slope is entirely positive. What does this suggest?
What is there is evidence of a strong, linear relationship