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The stem and leaf plot for the 26 estimates of elapsed time illustrates a grouping of the data by tens; for example, the first stem contains all values from 30 to 39. A stem and leaf plot, however, does not have to group the data by tens -- we could have grouped by fives, for instance. If we were grouping by fives, we would consider all possible numbers in the 50s, for instance, and then put them in two groups, the High and the Low:
Low Group | | High Group |
50 51 52 53 54 | 55 56 57 58 59 |
When forming the stems for a grouping by fives, we consider the second digit of each number as well as the first:
• | Numbers in the Low Group end with a second digit of 0, 1, 2, 3, or 4. |
• | Numbers in the High Group end with a second digit of 5, 6, 7, 8, or 9. |
Note that the two groups each have the same number of possible second digits (5). When creating a stem and leaf plot, all stems should have the same number of possible leaves.
To classify our 26 responses in this way, we set up our stem and leaf plot with stems corresponding to the Highs (H) and Lows (L) and then group the responses accordingly. For example, the first data value (63) is on stem 6L since its leaf, 3, is in the Low Group:
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26 Responses to the Question |
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63 |
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67 |
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79 |
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75 |
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57 |
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72 |
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52 |
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89 |
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39 |
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59 |
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55 |
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68 |
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66 |
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86 |
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70 |
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52 |
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60 |
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64 |
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42 |
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54 |
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56 |
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82 |
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57 |
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65 |
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59 |
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33 |
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