WGU D582 Intro to Stats for Research Study Guide

WGU D582 Intro to Stats for Research | Study Guide | Helpful Tips | 2025 Update with complete solutions.

• What is the difference between a population and a sample?

 Answer: A population includes all members of a defined group that we are studying or collecting information on, while a sample is a subset of the population selected for analysis.

• Define descriptive statistics.

 Answer: Descriptive statistics summarize and organize characteristics of a data set, including measures like mean, median, mode, and standard deviation.

• What is inferential statistics?

 Answer: Inferential statistics use data from a sample to make inferences or predictions about a population.

• Explain the term 'variable' in statistics.

 Answer: A variable is any characteristic, number, or quantity that can be measured or quantified.

• Differentiate between qualitative and quantitative variables.

 Answer: Qualitative variables describe non-numeric characteristics or categories, while quantitative variables represent numeric values.

• What is a nominal scale?

 Answer: A nominal scale classifies data into distinct categories without any order or ranking.

• Define ordinal scale.

 Answer: An ordinal scale classifies data into categories that have a meaningful order but unknown intervals between categories.

• What is an interval scale?

 Answer: An interval scale has ordered categories with known and equal distances between them but lacks a true zero point. 1 / 3

• Explain a ratio scale.

 Answer: A ratio scale has all the properties of an interval scale, and also includes a true zero point, allowing for the calculation of ratios.

• What is the mean of a data set?

 Answer: The mean is the average of all data points, calculated by summing them up and dividing by the number of points.

• Define median.

 Answer: The median is the middle value in a data set when the numbers are arranged in order.

• What is the mode?

 Answer: The mode is the value that appears most frequently in a data set.

• Explain range in statistics.

 Answer: The range is the difference between the highest and lowest values in a data set.

• What is variance?

 Answer: Variance measures the average squared deviation of each number from the mean of a data set.

• Define standard deviation.

 Answer: Standard deviation is the square root of the variance and indicates how spread out the numbers in a data set are.

• What is a frequency distribution?

 Answer: A frequency distribution is a summary of how often different values occur in a data set.

• Explain the purpose of a histogram.

 Answer: A histogram is a graphical representation of the distribution of numerical data, showing the frequency of data within certain ranges.

• What is a normal distribution? 2 / 3

 Answer: A normal distribution is a bell-shaped curve where most of the data points are concentrated around the mean, and it is symmetric about the mean.

• Define skewness.

 Answer: Skewness measures the asymmetry of the distribution of values in a data set.

• What does a positive skew indicate?

 Answer: A positive skew indicates that the tail on the right side of the distribution is longer or fatter than the left side.

• What does a negative skew indicate?

 Answer: A negative skew indicates that the tail on the left side of the distribution is longer or fatter than the right side.

• Define kurtosis.

 Answer: Kurtosis measures the "tailedness" of the distribution; high kurtosis indicates heavy tails, while low kurtosis indicates light tails.

• What is probability?

 Answer: Probability is a measure of the likelihood that an event will occur, expressed as a number between 0 and 1.

• Explain the difference between independent and dependent events.

 Answer: Independent events are those whose outcomes do not affect each other, while dependent events have outcomes that are influenced by each other.

• What is a probability distribution?

 Answer: A probability distribution shows how probabilities are distributed over the values of a random variable.

• Define discrete random variable.

 Answer: A discrete random variable is one that has countable outcomes, such as the number of heads in a series of coin flips.

• What is a continuous random variable?

 Answer: A continuous random variable can take any value within a given range, such as height or weight.

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