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2 weeks ago
Textbook authors must be careful that the reading level of their book is appropriate for the target audience. Some methods of assessing reading level require estimating the average word length. We've randomly chosen 20 words from a randomly selected page in Stats: Modeling the World and counted the number of letters in each word:

5, 5, 2, 11, 1, 5, 3, 8, 5, 4, 7, 2, 9, 4, 8, 10, 4, 5, 6, 6



For a more definitive evaluation of reading level the editor wants to estimate the text's word length to within 0.5 letters with 98% confidence. How many randomly selected words does she need to use?
Textbook 

Stats: Modeling the World


Edition: 4th
Authors:
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wrote...
Posts: 261
2 weeks ago
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First Estimate:
ME = z* × SE()
0.5 = 2.326 ×
n = 156.02 ≈ 157
Although not necessary, since 157 is quite large, we could find a better estimate using
, from Table T.
ME = t*140 × SE()
0.5 = 2.353 ×
n = 159.66 ≈ 160
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