Probability and Statistics, WGU C955 , 2024 Exam Questions With Complete Solutions.

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