Statistics final wgu academy exam questions and answers

Statistics final wgu academy exam questions and answers Categorical variables that there is no natural order among the categories nominal variables Categorical variables where there is natural order among the categories (low-high) ordinal variable A measurement which makes sense to talk about the difference between values but not the ratio between values interval Quantitive variables where is makes sense to talk about the difference in ratios. (Income, weight) ratio Value 0 means the absence of quantity (income $0) In ratios: Tells us what values the variables take and how often they take those values Distribution of a Variable Vale 0 does not mean the absence of value (temp = 0F) In intervals: Emphasize how the different categories relate to the whole Pie charts Emphasize how the different categories compare with each other Bar charts Breaking the range of values into intervals and count how many observations fall into interval. Histogram Graphical display of quantitive data. Data is spread into "stem" and "leaf". It retains the data and sorts. Stemplot(stem and leaf plot) Graphically represents the distribution of a quantitive variable. Visually displays the five number summary and the observations classified as a suspected outlier. Boxplot Mode, mean, and median. Measures of Center The most commonly occurring value. Can be unimodal or bimodal Mode The average of a set of observations. The sum of observations divided by the number of observations. (x bar) Mean The midpoint of the distribution. (M) Median Range, inter quartile range (IQR), standard deviation Measures of soread -order the data smallest to largest -if the number(n) of observations is odd (n+1)/2nd spot -if the number(n) of observations is even we have two n/2 = spot & n/2 + 1 = spot How to find the median Mean Measure of center that is sensitive to outliers Median Measure of center that is not sensitive to outliers Mean and median will be approximately equal Symmetric distributions Mean will be greater than the median skewed right Mean will be less than the median skewed left The exact distance between the smallest data point and the largest. The most intuitive measure of variability. range Measures the variability of a distribution by giving us the range covered by the MIDDLE 50% of the data. - Step 1: Arrange the data in increasing order, and find the median - Step 2: Find the median of the lower 50% of the data = 1st quartile (Q1) - Step 3: Repeat this again for the top 50% of the data = 3rd quartile (Q3) - Step 4: The middle 50% of the data falls between Q1 and Q3. Therefore: IQR = Q3 - Q1 Note: When finding the median of an odd number of data items, it is not included in either the bottom or top half of the data; when median is even, the data are naturally divided into two halves.