Fundamentals of Biostatistics
8th Edition
ISBN: 9781305268920
Author: Bernard Rosner
Publisher: Cengage Learning
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Textbook Question
Chapter 7, Problem 97P
An experiment was performed to assess the efficacy of an eye drop in preventing “dry eye.” A principal objective measure used to assess efficacy is the tear breakup time (TBUT),
which is reduced in people with dry eye and which the researchers hope will be increased after use of the eye drop.
In the actual study, participants will be randomized to either active drug or placebo, based on a fairly large sample size. However, a pilot study was first performed based on 14 participants. Under protocol A, the participants had their TBUT measured at baseline and were then instructed to not blink their eyes for 3 seconds, after which time the placebo eye drop was instilled. The TBUT was measured again immediately after instillation as well as at 5, 10, and 15 minutes postinstillation, during which time the study participants were in a controlled-chamber environment with low humidity to exacerbate symptoms of dry eye. On 2 other days participants received protocols B and C. Protocol B was identical to protocol A except that participants were told not to blink for 6 seconds prior to drop instillation. Protocol C was identical to protocol A except that participants were told not to blink their eyes for 10 seconds prior to drop instillation. Note that the same participants were used for each protocol and that for each protocol data are available for each of two eyes. Also, for each eye, two replicate measurements were provided.
The data are available in TEAR.DAT with documentation in TEAR.DOC at www.cengagebrain.com. For each protocol, TBUT (in seconds) was measured (1) at baseline (before drop instillation), (2) immediately after drop instillation, (3) 5 minutes after instillation, (4) 10 minutes after instillation, and (5) 15 minutes after instillation.
The standard protocol used in previous clinical studies of TBUT is a 6-second nonblink interval (protocol B). All the following questions concern protocol B data. For this purpose, average TBUT over two replicates and over both eyes to find a summary value for each time period for each participant.
Does the effect of the placebo eye drop change over time after drop instillation? (Hint: Compare mean TBUT at 5, 10, and 15 minutes postinstillation vs. mean TBUT immediately after drop instillation.)
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Chapter 7 Solutions
Fundamentals of Biostatistics
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Now...Ch. 7 - Prob. 89PCh. 7 - A screening program for neuroblastoma (a type of...Ch. 7 - A screening program for neuroblastoma (a type of...Ch. 7 - Prob. 92PCh. 7 - Prob. 93PCh. 7 - Prob. 94PCh. 7 - Prob. 95PCh. 7 - Prob. 96PCh. 7 - An experiment was performed to assess the efficacy...Ch. 7 - Medical errors are common in hospitals throughout...Ch. 7 - Prob. 99PCh. 7 - Prob. 100PCh. 7 - Prob. 101PCh. 7 - Prob. 102PCh. 7 - Prob. 103PCh. 7 - Prob. 104PCh. 7 - Osteoporosis is an important cause of morbidity in...Ch. 7 - Osteoporosis is an important cause of morbidity in...Ch. 7 - Osteoporosis is an important cause of morbidity in...Ch. 7 - Prob. 108PCh. 7 - Prob. 109PCh. 7 - Prob. 110PCh. 7 - Prob. 111PCh. 7 - Prob. 112PCh. 7 - Prob. 113PCh. 7 - A study was conducted in Sweden to relate the age...Ch. 7 - A study was conducted in Sweden to relate the age...Ch. 7 - A study was conducted in Sweden to relate the age...Ch. 7 - Prob. 117PCh. 7 - Prob. 118PCh. 7 - Prob. 119PCh. 7 - Prob. 120PCh. 7 - Prob. 121P
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