STA 2023 Exam 1 Questions and Answers Already Passed

STA 2023 Exam 1 Questions and Answers Already Passed Statistics - Answers the science of collecting, analyzing, interpreting, and presenting data Categorical - Answers data that is describing using words or categories, qualitative Quantitative - Answers data that is describing using numbers, can be averaged Graphical - Answers categorical and quantitative Categorical - Answers bar charts (bars do not touch) and pie charts Quantitative - Answers histograms (bars usually touch), stem plots, box plots, and dot plots Numerically - Answers center and spread Center - Answers mean, median, mode Mean - Answers the 'average', the balancing point, distances from the data points always add up to zero Median - Answers the middle ordered value, the 50th percentile, falls in (n+1)/2 position, always exactly 50% of the observations on either side of it and is not very sensitive to outlier, robust Mode - Answers the most frequently occurring number, the measure of center represents the most common observations or class of observations Spread - Answers range, variance, standard deviation, IQR Range - Answers min-max, the measure of spread that is affected most by outliers Variance - Answers represents the 'typical' squared distance from the mean, in squared units, measure of spread around the mean, but its units are not the same as those of the data points Standard deviation - Answers represents the 'typical' distance from the mean, in units of data, measure of spread that is smaller for distributions where the points are clustered around the middle, cannot be negative IQR - Answers interquartile range, Q3-Q1 where Q3= 75th percentile (the median of the 'top' half) and Q1= 25th percentile (the median of the 'bottom' half), gives the spread of the central (middle) 50% of the data set Outliers - Answers any observations that are significantly far away from the rest of the data points Skewed right - Answers mean->median->mode Normal - Answers bell curve, mean=median=mode Skewed left - Answers mean<-median<-mode Bimodal - Answers mean=median Bell shaped with an outlier - Answers mean>median Rectangular/uniform - Answers mean=median Discrete - Answers countable Continuous - Answers measurable Residuals - Answers vertical distance between the points and the line, sum to 0, error=actual-predicted Least square regression line - Answers minimizes the sum of the residuals squared b - Answers slope, as x increases by 1, y is predicted to increase/decrease by b a - Answers y intercept, when x=0, y is predicted to be a r - Answers correlation coefficient, sign of the slope, measures strength and direction, between -1 and 1, not affected by units of x and y r2 - Answers coefficient of determination, percent of variation in y that is explained by x, between 0% and 100%, 1-r2= the fraction of the varia