Summarizing Quantitative Data(KA/SAP/U3SummarizingQuantitativeData)
Unit 3: Summarizing Quantitative Data
Master the key concepts of summarizing quantitative data with explanations, interactive quizzes, and visualizations!
1. Measuring Center in Quantitative Data
The center of a data set can be described using the mean (average) or median (middle value). The mean is sensitive to outliers, while the median is more robust.
2. More on Mean and Median
The mean is calculated by adding all values and dividing by the number of values. The median is the middle value when data is ordered.
3. Interquartile Range (IQR)
The interquartile range (IQR) measures the spread of the middle 50% of data. IQR = Q3 - Q1, where Q1 is the first quartile and Q3 is the third quartile.
4. Variance and Standard Deviation of a Population
Variance measures the average squared deviation from the mean. Standard deviation is the square root of variance, showing how spread out the data is.
5. Variance and Standard Deviation of a Sample
For a sample, variance and standard deviation are calculated similarly, but we divide by (n-1) instead of n to account for sample bias.
6. More on Standard Deviation
Standard deviation is a key measure of spread. About 68% of data falls within 1 standard deviation of the mean in a normal distribution.
7. Box and Whisker Plots
A box plot shows the minimum, Q1, median, Q3, and maximum of a data set. It helps visualize the spread and identify outliers.
8. Other Measures of Spread
Other measures include range (max - min) and outliers (values far from the rest). Outliers can affect mean and standard deviation.
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