WGU C955 Questions And Answers

WGU C955 Histogram - ANS A graphical representation -- bars, measuring the frequency within each interval Skewed right - ANS Not a symmetric distribution, the tail is on the right Measures of center - ANS Median, the mean (and mode) Measures of spread - ANS Range, IQR & standard deviation Standard Deviation Rule - ANS 68% of the data are within 1 standard deviation, 95% are within 2, 99.7% are within 3 standard deviations from the mean. median (for center) & IQR (for spread) - ANS skewed data uses these for center and spread Scatter plot - ANS A graphical representation of Q - Q Two way table - ANS A graphical representation of C - C Side-by side box - ANS A graphical representation of C - Q Interpolation - ANS Making predictions *within* the range of your data. This is usually accurate. Extrapolation - ANS Making predictions *outside* of the range of your data. This is generally a bad idea. Simpson's Paradox - ANS When split up, each data set can have a pattern which goes away when all the data is combined. Prospective study - ANS Is a study that's done over time to find results / A study watching for outcomes during the study period Unbalanced response - ANS Giving more options that are negative than positive options (or vice versa) which biases the responses towards the more common option Matched pairs - ANS Grouping two similar subjects and giving different treatments/procedures to each in order to compare the differences. For example, having one twin take a medication while the other twin does not. Population - ANS The entire group you are trying to describe or understand. Sampling frame - ANS List of group from which you choose your sample. Sample - ANS The group that is actually picked to be included in a study Simple random sample - ANS making a selection by following a random pattern and selecting without replacement. Unbiased. Systematic sample - ANS Sample is selected by listing the sampling frame, then making a selection by following a simple pattern (eg. Every 20th name). Unbiased. Voluntary sample - ANS Members of the sample may choose not to respond. Similar to Non Response. Convenience sample - ANS Participants are easy for researcher to access. Tends to increase bias. Cluster sample - ANS Sample frame is divided into groups, we select a few groups, then selecting ALL of the members of those groups. Stratified sample - ANS Sample frame is divided into groups. Then we choose a random sample (usually the same size) from within EVERY group. Multi-stage sample - ANS Multiple rounds of randomness and grouping. For example: randomly selecting a few groups, then choosing a small random sample just those selected groups. Often a combination of Cluster and Stratified Sampling. P(A)*P(B) - ANS independent events: P(A and B) = P(A|B) - ANS P(A and B) ÷ P(B) P(A or B) - ANS P(A) + P(B) - P(A and B) P(A and B) - ANS P(A)*P(B|A) Box plot - ANS an image that has 5 number summary: min, Q1, median, Q3, max, nCr = n! / r!(n - r)! - ANS probability combination formula