Sta1502 Exam Pack 2024 Questions With Complete Solutions

Mean - correct answer Sum of all scores divided by the number of scores Median - correct answer Middle score when scores are order (half of scores are above it, half are below it. Mode - correct answer The most frequent score Variance - correct answer variance measures how far each number in the set is from the mean (average) Standard deviation - correct answer Average deviation of a value from the mean Normal distribution - correct answer Bell shaped and symmetrical around the center Skew - correct answer The symmetry of the distribution Positive skew - correct answer Scores cluster at the low values with the tail pointing at the high values Negative Skew - correct answer Scores cluster at the high values with the tail pointing to low values Kurtosis - correct answer The "heaviness" of the tails Positive Kurtosis - correct answer Heavy tails Negative Kurtosis - correct answer Light tails Deviation - correct answer Deviation is the difference between the mean and an actual data point Sum of squared errors - correct answer Add the squared errors (good measure for overall variability Sum of squares, variance, and standard deviation all represent: - correct answer The same thing; the fit of the mean to the data, the variability in the data, the error Population - correct answer The collection of units to which we want to generalize a set of findings or a statistical model Sample - correct answer A smaller collection of units from a population is used to determine truths about that population Nominal scale - correct answer Binary (ex: M or F) Ordinal Scale - correct answer Non mathematical Frequency, happiness Interval - correct answer Difference between measurements but no true 0 (ex: Ratio scale - correct answer Differences between measurements, true 0 exists one-tailed test - correct answer Tests a directional hypothesis (ex: increase in investment leads to increase in sales) Two tailed test - correct answer Tests a non directional hypothesis (ex: increase in investment leads to change in sales positive or negative) T test - correct answer Can be done when only one independent variable that is manipulated in only two ways and only one outcome is measured Dependent t test - correct answer Compares two means based on related data (ex: data measured from same people at different times) Independent t test - correct answer Compares two means based on independent data (ex: data comes from two different groups of people) Standard error - correct answer The standard deviation of sample means Covariance - correct answer An unstandardized version of the correlation coefficient, a measure of the strength of relationship between two variables, dependent on the units of measurement of the variables (which is the main problem with covariance, the solution is to standardize it by dividing the covariance by the standard deviation of both variables, this is person's correlation coefficient) Effect size - correct answer A standardized measure of the effect size pearsons r, cohens d, odds ratio/risk rates How to interpret effect size (pearsons r) - correct answer .1 small effect .3 medium effect .5 large effect