f 4 ntroduction to Probability and Statistics A1 Assignment 1 his assignment has a total of 100 marks and counts 8% towards your final course grade. Chapter 1: (12 marks) For the study summarized in the abstract below: a. Identify the "5 W's plus H." b. Name each variable and identify whether it is categorical or quantitative. For each quantitative variable, identify the units used. Annals of Internal Medicine 2007 Jan 2;146(1):1-9 Effects of folic acid supplementation on hearing in older adults: a randomized, controlled trial. Durga J. Verhoef P. Anteunis LJ, Schouten E, Kok FJ. Wageningen University and Wageningen Centre for Food Sciences, Wageningen, The Netherlands. BACKGROUND: Age-related hearing loss is a common chronic condition of elderly persons. Low folate status has been associated with poor hearing. OBJECTIVE: To determine whether folic acid supplementation slows age-related hearing loss. DESIGN: Double-blind, randomized, placebo-controlled trial conducted from September 2000 to December 2004. SETTING: The Netherlands. PARTICIPANTS: 728 older men and women recruited from municipal and blood bank registries with plasma total homocysteine concentrations 13 micromol/L or greater, serum and vitamin B12 concentrations 200 pmol/L or greater at screening, and no middle ear dysfunction, unilateral hearing loss, or pathologic ear conditions unrelated to aging. INTERVENTION: Daily oral folic acid (800 microg) or placebo supplementation for 3 years. MEASUREMENTS: 3-year change in hearing thresholds, assessed as the average of the pure-tone air conduction thresholds of both ears of the low and high frequencies. RESULTS: Initial median hearing thresholds were 1 1.7 dB (interquartile range, 7.5 to 17.5 dB) for low frequencies and 34.2 dB (interquartile range, 22.5 to 50.0 dB) for high frequencies. Sixteen participants (2%) were lost to follow-up. After 3 years, thresholds of the low frequencies increased by 1.0 dB (95% CI, 0.6 to 1.4 dB) in the folic acid group and by 1.7 dB (CI, 1.3 to 2.1 dB) in the placebo group (difference, -0.7 dB [CI. -1.2 to -0.1 dB]: P = 0.020). Folic acid supplementation did not affect the decline in hearing high frequencies. LIMITATIONS: The strict criterion for participation on the basis of serum homocysteine concentrations limits extrapolation to the general population. Folic acid fortification of food was prohibited in the Netherlands during the study. so baseline folate levels in participants were about half of those found in the U.S. population. CONCLUSIONS: Folic acid supplementation slowed the decline in hearing of the speech frequencies associated with aging in a population from a country without folic acid fortification of food. The effect requires confirmation. with folic acid fortification