Variables and Data
Both weight and height are examples of which type of variable?
Ratio
What is an example of a measure of central tendency and a measure of variability?
Central Tendency: Mean, Median, Mode
Variability: Range, Standard Deviation, Variance
Z-test and t-test: two means
ANOVA: more than two means
What is the type and strength of a correlation with a Pearson's r value of -0.163?
Negative, Weak
What type of variables does chi-square determine correlation for?
Categorical
Dog breed, Pet type, and Subject Major are examples of which type of variable?
Categorical
Which measure of central tendency is most affected by outliers?
Mean
What is a difference between the two-samples t-test and the two-samples z-test?
Two-samples z-test requires the data to be normally distributed (and/or large sample size)
What is the difference in how variables change between a positive and negative correlation?
Positive correlation - variables change in the same direction; variables vary together
Negative correlation - variables change in the opposite direction
What quantitative values does chi-square use to calculate a correlation coefficient?
Olympic Medals are an example of which type of variable?
Ordinal
Which measure of variability represents the average distance of all the datapoints from the mean?
Standard Deviation
What does ANOVA on its own indicate?
If there is a statistically significant difference between two or more groups being compared.
What does the R-squared value in a regression analysis tell us?
The percentage of variance in the dependent variable that is accounted for by the independent variable.
What type of frequencies does chi-square use to determine correlation?
Observed and expected frequencies
What can be done with a categorical variable to make it produce quantitative data?
It can be coded with an interval scale
What is the difference between measures of central tendency and measures of variability?
Measures of central tendency reflect the center of a dataset; measures of variability reflect the extent to which the data is spread out or scattered.
If Lavene's test is not met, which t-value and p-value are used? (HINT: It has to do with variance)
Equal variance not assumed
What does the ANOVA output table tell us in a regression analysis?
If the regression line/model is a good predictor of the dependent variable based on the independent variable
What is likely to be true about the observed and expected frequencies if chi-square is significant?
They are different
Which type of variable is most commonly used in analyses?
Interval/ratio
Which descriptive statistic is a squared value?
Variance
If Lavene's test is not met, what does this imply for ANOVA?
An alternative must be used - welch's f, or brown-forsthye f
They will have good/strong predictive ability
How are degrees of freedom (df) calculated for chi-square?
df = (r-1)(c-1)
df = (# rows - 1)(# columns - 1)