Analysis of Scientific Data - Semester 2, 2021 Week 2 Tutorial - Exercises Part A This is a short quiz to check you know the important ideas about logarithms. Without using a calculator (answers should have no decimal places), simplify the following as much as possible: 1. log10 10 = 2. log10 1000 = 3. log10 1 = 4. log10 0.01 = 5. log10(10x) = 6. log10 200 = 7. log10 0 = 8. log2 16 = 9. log2 * = 10. loge 2.718282 ~
Part B A high-fat diet (HFD) is known to have a negative effect on bone quality in young and old people. A study was undertaken to evaluate the effects of an HFD on bone healing in growing female rats. Twenty-six postweaning female rats were randomly assigned to two groups (13 per group): a standard diet (SD) group and an HFD (with 60% of energy from fat) group. The rats were maintained under standard laboratory conditions at a temperature of 22 + 2 ? and humidity of 55 + 5 % with a 12-hour light and dark cycle and with free access to water and food. The rats received the assigned diets for 5 weeks, and in the third week they were submitted to an osteotomy procedure (i.e. bone cut) of the left tibia. At the end of the 5 weeks, the rats were euthanised and the tibiae were removed for mechanical testing. The mechanical testing involved a force begin applied to the tibia at a speed of 1.0 mm/min to generate a tension load on the osteotomy site. The maximal load (N) and stiffness (N/mm) were measured. Lower maximal load (p = 0.040) and bending stiffness (p = 0.020) were observed in tibiae of HFD rats compared to SD rats. (a) What type of variable is maximal load? Dependent (discrete) variable. (b) What type of variable is diet? Independent (ordinal) variable. (c) Which variable is the variable of interest, that is the response variable? Maximal load and stiffness. (d) What type of study is this? This is a randomised comparative study. (e) What would be a suitable null hypothesis associated with the p-value for maximal load? H(0) : The use of a high-fat diet within rats did not influence the maximal load or stiffness of rat tibia. (f) What are we able to conclude about the effect of diet on bone maximal load following osteotomy? In terms of rats, one may propose that a higher fat diet decreases the maximal load and flexibility stiffness of rat bone tissue. Reference J.S Yamanaka, G.R. Yanagihara, B.L. Carlos, J. Ramos, B.B. Brancaleon, A.P. Macedo, J.P.M Issa & A.C. Shimano (2018) A high-fat diet can affect bone healing in growing rats, Journal of Bone and Mineral Metabolism, 36, 255-263. doi: 10.1007/s00774-017-0837-4