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Percentiles And Quartiles In Statistics | Percentiles And Quartiles Explained |

Percentiles and quartiles are fundamental building blocks for statistics and data analysis. This Percentiles and Quartiles in Statistics video will make you understand what percentiles and quartiles are and how to calculate each of them with the help of an example. You will learn how to interpret each measure.<br><br>In this tutorial, you will learn about:<br>1. What are percentiles?<br>2. How to calculate percentiles?<br>3. What are quartiles?<br>4. How to calculate quartiles?

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Percentiles And Quartiles In Statistics | Percentiles And Quartiles Explained |

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  1. What’s in it for you? What is Percentile? How to calculate Percentile? What are Quartiles? How to calculate Quartiles?

  2. Percentiles

  3. Click here to watch the video

  4. What is Percentile? Percentile is a measure used to indicate the value below which a given percentage of observations fall x(n + 1) Px = 100 Px = The value at which x percentage of data lie below that value n = Total number of observations

  5. How to calculate Percentile? Suppose you have the marks of 20 students Marks Scored Out Of 100

  6. How to calculate Percentile? Let’s find the 90th percentile Sorted Marks Sort the data in ascending order

  7. How to calculate Percentile? Let’s find the 90th percentile 90(20 + 1) P90 = 100 Sorted Marks 1890 P90 = 100 P90 = 18.9 ~ 19 P90 = 94

  8. How to calculate Percentile? Let’s find the 90th percentile Sorted Marks P90 = 94 means that 90% of students got less than 94 and 10% of students got more than 94 P90 = 18.9 ~ 19 P90 = 94

  9. How to calculate Percentile? Let’s find the percentile for marks 78 P= * 100 N 12 * 100 P= 20 Sorted Marks n = Ordinal rank of values N = Total values in the dataset n P= 60

  10. Quartiles

  11. What are Quartiles? A quartile divides a sorted data set into 4 equal parts, so that each part represents ¼ of the data set

  12. What are Quartiles? A quartile divides a sorted data set into 4 equal parts, so that each part represents ¼ of the data set Original Data FirstQuartile Q1 Third Quartile Q3 Second Quartile Q2

  13. What are Quartiles? A quartile divides a sorted data set into 4 equal parts, so that each part represents ¼ of the data set Original Data LowerQuartile Upper Quartile Median

  14. What are Quartiles? 50% of all the data has a value ≤ M 25% of all the data has a value ≤ Q1 50% of all the data lies between Q1 and Q3 75% of all the data has a value ≤ Q2 FirstQuartile Q1 Third Quartile Q3 Second Quartile Q2

  15. What are Quartiles? If a measurement falls to the right of the upper quartile of a set of data, then we know that it is in the top 25% of the data FirstQuartile Q1 Third Quartile Q3 Second Quartile Q2

  16. What are Quartiles? If a measurement falls to the left of the lower quartile of a set of data, then we know that it is in the bottom 25% of the data FirstQuartile Q1 Third Quartile Q3 Second Quartile Q2

  17. How to calculate Quartiles? Let’s consider we have the petal lengths of rose flowers

  18. How to calculate Quartiles? To find Q1, Q2 and Q3, we need to first sort the data in ascending order sort

  19. How to calculate Quartiles? Find the Median = Middle value in the dataset, which is the second quartile n = 15 Since n is odd, median = (n + 1)/2 Median = 16/2 = 8 Q2 is the 8th observation = 3.3

  20. How to calculate Quartiles? Find the Median = Middle value in the dataset, which is the second quartile = Median Q2

  21. How to calculate Quartiles? Find the First Quartile value = Q1 Q1 = (n + 1) x (1/4) Q1 = 16/4 = 4 Q1 is the 4th observation = 2.0

  22. How to calculate Quartiles? Find the First Quartile value = Q1 = First Quartile Q1

  23. How to calculate Quartiles? Find the Third Quartile value = Q3 Q3 = (n + 1) x (3/4) Q3 = 16x(3/4) = 12 Q3 is the 12th observation = 4.2

  24. How to calculate Quartiles? Find the Third Quartile value = Q3 = Third Quartile Q3

  25. How to calculate Quartiles? Find the Third Quartile value = Q3 = First Quartile Q1 = Second Quartile Q2 = Third Quartile Q3

  26. Quartile Summary 1.1,1.3, 1.5, 2.0, 2.6, 2.7, 2.9, 3.3, 3.8, 3.8, 4.0, 4.2, 4.5, 5.1, 5.6 25% 25% 25% 25% Q1 Q2 Q3 • ¼ or 25% of the flowershavea petal length that is less than or equal to2.0 cm • ½ or 50% of the flowers have apetal length that is less than or equal to3.3 cm ½ or 50% of the flowers have a petal length between 2.6 cm and 4.2 cm • • ¾ or 75% of the flowers have apetal length that is less than or equal to4.2 cm

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