The following appeared in a memo from the director of a large group of hospitals.
"In a controlled laboratory study of liquid hand soaps, a concentrated solution of extra strength UltraClean hand soap produced a 40 percent greater reduction in harmful bacteria than did the liquid hand soaps currently used in our hospitals. During our recent test of regular-strength UltraClean with doctors, nurses, and visitors at our hospital in Worktown, the hospital reported significantly fewer cases of patient infection (a 20 percent reduction) than did any of the other hospitals in our group. The explanation for the 20 percent reduction in patient infections is the use of UltraClean soap."
In his memo, the director of a large group of hospitals argues that the 20\% reduction in patient infection in the hospital in Worktown is explained by the use of the UltraClean soap. To corroborate his argument, he cites a recent laboratory study according to which the UltraClean soap produced a greater reduction in harmful bacteria. Although the causal relation the director establishes is not implausible, other explanations to the observed relation must be checked and refuted to support the argument.
First, the reduction in patient infection in the Worktown Hospital may reflect some of its specific characteristics. It may turn out, for instance, that the personnel in the hospital is more experienced or cautious, and thus provides the patients with better protection. The hospital may also be larger and contain more rooms, allowing thereby to place fewer patients in each room and reduce the chances of spreading infections.
Second, the city of Worktown may also have specific characteristics that affect infection odds. Its population may be younger and healthier than the population in other cities where the group's hospitals operate, and thus more immune to infections. Indeed, various studies indicate that good health reduces the chances to get infected, which is, in any case, a much more important factor than the specific soap used in the hospital.
Third, the fact that a test was conducted in the hospital may induce a more prudent behavior on the part of the doctors and the nurses. Although the test does not officially check their conduct, merely being supervised would probably make the personnel more alarmed. If such an explanation holds, then testing any other soap would produce similar positive results, which would have nothing to do with its particular solution.
The kind of soap used in hospitals may be an important factor in reducing patient infections. However, to prove that a specific soap is indeed better than others, a few not less plausible explanations must be ruled out. The group of hospitals would thus have to check for the city's and the hospital's specific characteristics and run additional experiments using different soaps, to exclude the possibility of any psychological effect generated by the test.
Comments
e-rater score report
Attribute Value Ideal
Final score: 4.5 out of 6
Category: Good Excellent
No. of Grammatical Errors: 1 2
No. of Spelling Errors: 1 2
No. of Sentences: 15 15
No. of Words: 362 350
No. of Characters: 1855 1500
No. of Different Words: 186 200
Fourth Root of Number of Words: 4.362 4.7
Average Word Length: 5.124 4.6
Word Length SD: 2.82 2.4
No. of Words greater than 5 chars: 139 100
No. of Words greater than 6 chars: 117 80
No. of Words greater than 7 chars: 87 40
No. of Words greater than 8 chars: 49 20
Use of Passive Voice (%): 0 0
Avg. Sentence Length: 24.133 21.0
Sentence Length SD: 5.931 7.5
Use of Discourse Markers (%): 0.733 0.12
Sentence-Text Coherence: 0.354 0.35
Sentence-Para Coherence: 0.608 0.50
Sentence-Sentence Coherence: 0.092 0.07
Number of Paragraphs: 5 5
Transition Words or Phrases used:
also, first, however, if, may, second, so, then, third, thus, for instance, kind of, in any case
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 12.0 19.6327345309 61% => OK
Auxiliary verbs: 13.0 12.9520958084 100% => OK
Conjunction : 10.0 11.1786427146 89% => OK
Relative clauses : 10.0 13.6137724551 73% => More relative clauses wanted.
Pronoun: 14.0 28.8173652695 49% => OK
Preposition: 43.0 55.5748502994 77% => OK
Nominalization: 16.0 16.3942115768 98% => OK
Performance on vocabulary words:
No of characters: 1906.0 2260.96107784 84% => OK
No of words: 362.0 441.139720559 82% => More content wanted.
Chars per words: 5.26519337017 5.12650576532 103% => OK
Fourth root words length: 4.36191444098 4.56307096286 96% => OK
Word Length SD: 2.88179676629 2.78398813304 104% => OK
Unique words: 187.0 204.123752495 92% => More unique words wanted.
Unique words percentage: 0.516574585635 0.468620217663 110% => OK
syllable_count: 587.7 705.55239521 83% => OK
avg_syllables_per_word: 1.6 1.59920159681 100% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 4.0 4.96107784431 81% => OK
Article: 9.0 8.76447105788 103% => OK
Subordination: 3.0 2.70958083832 111% => OK
Conjunction: 2.0 1.67365269461 119% => OK
Preposition: 5.0 4.22255489022 118% => OK
Performance on sentences:
How many sentences: 15.0 19.7664670659 76% => Need more sentences. Double check the format of sentences, make sure there is a space between two sentences, or have enough periods. And also check the lengths of sentences, maybe they are too long.
Sentence length: 24.0 22.8473053892 105% => OK
Sentence length SD: 35.3739389319 57.8364921388 61% => OK
Chars per sentence: 127.066666667 119.503703932 106% => OK
Words per sentence: 24.1333333333 23.324526521 103% => OK
Discourse Markers: 6.4 5.70786347227 112% => OK
Paragraphs: 5.0 5.15768463074 97% => OK
Language errors: 0.0 5.25449101796 0% => OK
Sentences with positive sentiment : 8.0 8.20758483034 97% => OK
Sentences with negative sentiment : 3.0 6.88822355289 44% => More negative sentences wanted.
Sentences with neutral sentiment: 4.0 4.67664670659 86% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.171808938351 0.218282227539 79% => OK
Sentence topic coherence: 0.0667817576711 0.0743258471296 90% => OK
Sentence topic coherence SD: 0.0774996837769 0.0701772020484 110% => OK
Paragraph topic coherence: 0.10707028176 0.128457276422 83% => OK
Paragraph topic coherence SD: 0.0912225624416 0.0628817314937 145% => OK
Essay readability:
automated_readability_index: 15.5 14.3799401198 108% => OK
flesch_reading_ease: 47.12 48.3550499002 97% => OK
smog_index: 8.8 7.1628742515 123% => OK
flesch_kincaid_grade: 12.7 12.197005988 104% => OK
coleman_liau_index: 13.58 12.5979740519 108% => OK
dale_chall_readability_score: 9.28 8.32208582834 112% => OK
difficult_words: 102.0 98.500998004 104% => OK
linsear_write_formula: 14.0 12.3882235529 113% => OK
gunning_fog: 11.6 11.1389221557 104% => OK
text_standard: 14.0 11.9071856287 118% => OK
What are above readability scores?
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Rates: 75.0 out of 100
Scores by essay e-grader: 4.5 Out of 6
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Note: the e-grader does NOT examine the meaning of words and ideas. VIP users will receive further evaluations by advanced module of e-grader and human graders.