inameisla eniwollol DESCRIBING THE DATA EXCERPT FROM THE RESEARCH ARTICLE Mean and Range to yhoenib to beatani Cancer Risk-Reduction Behaviors Table 1 Physical Activity (Mean Hours/Day Averaged over 7 Days) Activity Level Range To noletusdid not choiteeup Sleep 7.35 5.5-8.8 Light physical activity 8.71 3.0-16.0 Moderate physical activity 3.36 of pizioW .71-8.3 STATISTICAL GUIDE Hard physical activity 0-4.1 batalamos .78 Very hard physical activity .14 0-1.05 The range is the difference between the highest and the lowest scores in a set of scores. (Some statisticians add "1" to the differ- ence.) Sometimes researchers merely report the highest and lowest see To review the mean STUDY QUESTIONS values (without subtracting) and refer to the two values as the range. see Exercise Other times, a single number is reported for the range, and in this Factual Questions case, the single number is the difference between the highest and 1. On the average, how many 7. Did some of the women report lowest score. fou hours per day did the women engaging in no "Hard physical The range is one indicator of how dispersed or spread out a set of sleep ? activity"? Explain. scores is. The range is important because it gets at the idea of variation 2. On the average, how many 8. Did any of the women report or variability in a distribution-one of the key features of a distribution. hours a day did the women engaging in more than an hour engage in "Light physical of "Hard physical activity"? If the range is small, the variation is small and vice versa. activity"? Explain . By the way, the terms variation, spread, and dispersion are often 3. On the average, which type of 9. Is there more variation in used interchangeably. They all point towards a central idea-the physical activity was engaged "Hard physical activity" or in amount of difference in the scores, one from another, in a distribution. in for the fewest number of "Very hard physical activity"? The range is the most straightforward way to calculate the variation or hours ? Explain. spread in a distribution. It is also the most conceptually simple way to 4. Did the women average more 10. Is the mean for "Hard physi- than an hour a day of "Hard cal activity" closer to one end think about variation in a distribution. Still, the range as a description physical activity"? of the range than the other? If of variation has its limitations, which is why other methods to calcu- 5. Which physical activity had so, which one ? late the variation are needed. The rest of the exercises in Unit ll cover the largest range? Why do 11. What explains your answer in many of the further ways to think about and calculate the variation in you think this activity had the question 10? a distribution. largest range of responses? 6. What is the smallest number of hours of sleep reported? BACKGROUND NOTE The researchers who reported the information below were studying the Questions for Discussion physical activity of women who had survived breast cancer. The women 12. In your opinion, what are the to using self-reports for gath- in the study self-reported their levels of physical activity (i.e., their activities advantages and disadvantages ering data on physical activities were not observed by the researchers)
