unit 4 Flashcards
What is the focus of bivariate descriptive statistics?
Bivariate descriptive statistics focuses on the relationship between two variables.
What does it mean for two variables to have a relation?
A relation between two variables means that they vary jointly, at the same time.
What is the difference between relation and causality?
Relation means two variables change together, while causality means one variable causes a change in another.
What are joint frequencies?
Joint frequencies are the frequency shared by some values of two variables.
What is a contingency table?
A contingency table is a table that shows the joint frequencies of two categorical variables.
What are marginal distributions in a contingency table?
Marginal distributions are the absolute frequencies for each category in each variable in a contingency table.
Can contingency tables be created with relative frequencies and percentages?
Yes, contingency tables can be created with relative frequencies and percentages, similar to frequency distribution tables.
What type of variables are contingency tables most frequently used with?
Contingency tables are most frequently used with categorical variables.
What is a grouped bar diagram used for?
A grouped bar diagram is used for the graphical representation of categorical variables in bivariate analysis.
What is the Chi-Square correlation index used for?
The Chi-Square correlation index is used to quantify the degree of relationship between two categorical variables.
What does the Chi-Square index measure?
The Chi-Square index measures the difference between observed and expected frequencies.
How are expected frequencies determined?
Expected frequencies are determined by assuming no association between variables, and that all frequencies would be equally distributed.
What does a greater difference between observed and expected frequencies mean for the Chi-Square value?
A greater difference between observed and expected frequencies results in a higher Chi-Square value, indicating a stronger association.
How do you calculate the expected frequency for a cell in a contingency table?
The expected frequency is calculated by multiplying the marginal distribution in variable X by the marginal distribution in variable Y, then dividing by the sample size.
What does a Chi-square of 0 indicate?
A Chi-square of 0 indicates no association between the two categorical variables.
What are the steps to calculate Chi-Square?
The steps to calculate Chi-Square are: (1) Build the contingencies table (observed frequencies), (2) Create a table with the expected frequencies, and (3) Use the Chi-square formula.
What is a dispersion diagram or scatter plot used for?
A dispersion diagram or scatter plot is used to visualize the relationship between two quantitative variables.
What is linear correlation?
Linear correlation describes the relationship when two variables covary together.
What is a positive or direct correlation?
A positive or direct correlation means that when values are high in one variable, they are also high in the other.
What is a negative or inverse correlation?
A negative or inverse correlation means that when values are high in one variable, they are low in the other.
What is a non-linear correlation?
A non-linear correlation is a relationship between variables that cannot be described by a straight line, such as a quadratic relationship.
What does the covariance index measure?
The covariance index measures the degree of linear relationship between two variables.
What information does the covariance index provide?
The covariance index allows us to know the direction of the relationship (positive/negative).
How is the covariance calculated?
The covariance is the average of the products of the deviation scores of the two variables.
