WGU C995 Exam Questions & Answers Accurate 100%

quantitative data - Answer Quantitative data consists of data values that are numbers, representing quantities that can be counted or measured. The Empirical Rule - Answer According to The Empirical Rule, approximately 68% of the data points in a dataset will be within 1 standard deviation of the mean. 95% of all values are within 2 standard deviations of the mean. Normal distribution - Answer In a normal distribution data is symmetrical, so the mean, median, and mode are all equal. measure of spread - Answer Measures of spread describe how similar or varied the set of observed values are for a particular variable (data item). Measures of spread include the range, quartiles and the interquartile range, variance and standard deviation. Standard Deviation Rule 2 and 3 deviations - Answer According the the Standard Deviation Rule, approximately 2.35 percent of all values will fall between 2 and 3 standard deviations above the mean. How are the mode and mean of a sample related if the distribution is positively skewed? - Answer The mode is less than the mean. A set of data is normally distributed with a mean of 85 and standard deviation 20. The data point values that fall within one standard deviation range from ___________ to ___________? - Answer We know that the standard deviation is 20. To obtain the values that are one standard deviation above and below the mean, we do the following: To obtain the first value, we will subtract 20 from the mean: 85 −20 =65 To obtain the second value, we will add 20 to the mean: 85 +20 =105 Therefore, the data values that will fall within 1 standard deviation of the mean will range from 65 to 105. best used to display categorical data - Answer How are the mean, median, and mode of a sample related if the distribution is normally distributed? - Answer The values are all equal IQR (interquartile range) - Answer Q3-Q1 standard deviation - Answer Using the Standard Deviation Rule, we know that when data is normally distributed, 50% of the values fall above the mean, and 50% of the values fall below the mean. population sample from a box plot. - Answer It is not possible to estimate the size of the population sample from a box plot. Pie chart - Answer A pie chart is the best type of graph to use to show categorical data, where each category represents a share of the total as a percent. Scatterplot - Answer A scatterplot is a graphical display that shows the explanatory variable on the x-axis and the response variable on the y-axis. Is useful when both variables in the data set are quantitative. Cluster - Answer If several points are grouped together away from the majority of points, we call them a cluster. two-way frequency table. - Answer The best method to display two categorical (words) variables is a two-way frequency table. Has rows and columns Side-by-side box plots - Answer Side-by-side boxplots are useful when the explanatory variable is categorical and the response variable is quantitative. Simpson's Paradox - Answer A counterintuitive situation in which a trend in different groups of data disappears or reverses when the groups are combined. Simpson's paradox is avoided by having an equal number of subjects exposed to each of the treatments in each trial. association - Answer A pattern or relationship between two variables. causal relationship - Answer A relationship between two variables that can be classified as cause-and-effect. causation - Answer A relationship of cause and effect between two or more variables. cluster sample - Answer Similar to stratified sample, but researchers select entire chunks or clusters of the population to obtain the study sample. coordinate plane - Answer A tool for graphing consisting of a horizontal x-axis and a vertical y-axis. correlation coefficient - Answer A measure of the linear relationship between two attributes. The numerical value demonstrates how closely the attributes vary together. Correlation coefficients near -1 and +1 have strong linear correlation, while a correlation coefficient near 0 has weak (or no) linear correlation. correlation - Answer An observed relationship between two quantitative variables. While this is most commonly a linear relationship, it does not need to be. Note that observing a relationship does NOT imply that there is a meaningful causal link between the variables. degree - Answer The largest exponent in a mathematical expression or equation. experimental study - Answer The researcher applies a treatment to one group and no treatment (or placebo) to a control group, to determine if there is causation between variables. extrapolate - Answer Using information from a data set to make predictions about data outside of the original set. hypothesis test - Answer A statistical test that tells us whether a result is significant. least squares - Answer A technique for finding the regression line. Least squares is the criteria by which the best-fit line is selected for paired data. It is a method that minimizes the squared distances of data points from a line that captures the trend in paired data. linear extrapolation - Answer Estimation using the linear regression equation is made outside known data points. linear interpolation - Answer Estimation using the linear regression equation in between known data points. lurking variable - Answer A variable that is not included in an analysis but that is related to two (or more) other associated variables which were analyzed. negative correlation - Answer A linear relationship between two quantitative variables in which the dependent variable increases as the independent variable decreases. observational study - Answer The researcher observes if there is an association between variables. There is no treatment or control group. p-value - Answer The probability that a result was caused by chance. population - Answer All subjects in the study which have the characteristics being evaluated. positive correlation - Answer A linear relationship between two quantitative variables in which the dependent variable increases as the independent variable increases. regression analysis - Answer A statistical analysis tool that quantifies the relationship between a response variable and one or more explanatory variables. Examples: Extrapolation Lurking variables Inappropriate sampling regression equation - Answer An equation used to model the relationship between the response and explanatory variables in a regression. regression line - Answer The line of best fit to show the relationship between variables, the one that minimizes distance from each data point to the line. representative sample - Answer A subset of the population with similar characteristics to the entire population. sample - Answer The subset of the study population that is being studied. sampling frame - Answer The list of all people or things that may be included in the statistical study.