Probability and Statistics, WGU C955.docx

Boxplot - correct answer an image that has min, Q1, median, Q3, max Histogram - correct answer A graphical representation -- bars, measuring the frequency within each interval Skewed right - correct answer Not a symmetric distribution, the tail is on the right, i.e. extra stuff on the right Measures of center - correct answer Median, the mean (and mode) Measures of spread - correct answer Range, IQR & standard deviation Standard Deviation Rule - correct answer 68% of the data are within 1 standard deviation, 95% are within 2, 99.7 are within 3 standard deviations from the mean. For skewed data, use these for center and spread - correct answer In this situation, we use median (for center) & IQR (for spread) Explanatory variable - correct answer In a study, what we think is the "cause" Response variable - correct answer In a study, what we think is the "effect" Scatter plot - correct answer A graphical representation of Q - Q Two way table - correct answer A graphical representation of C - C Side-by side box - correct answer A graphical representation of C - Q Linear relationship - correct answer "shaped like a line" Correlation coefficient, r - correct answer Between -1 and 1; measures how close the points are to the line and if the trend is uphill (positive) or downhill (negative). r = -0.2, for example - correct answer This is an example of a correlation coefficient that represents a weak negative correlation. r = 0.9, for example - correct answer This is an example of a correlation coefficient that represents a strong positive correlation. Linear regression line - correct answer A line that fits the data as close as possible, used to make predictions Interpolation - correct answer Making predictions *within* the range of your data. This is usually accurate. Extrapolation - correct answer Making predictions *outside* of the range of your data. This is generally a bad idea. Simpson's Paradox - correct answer When split up, each data set can have a pattern which goes away when all the data is combined. Only way to prove causation - correct answer Experiments, because they account for lurking variables Observational study - correct answer A type of study where we measure or survey members of a sample without trying to affect them. Cannot prove causation. Experimental study - correct answer A study where you split subjects up randomly and impose a change on one group to study the effect; can prove causation