What would be the expected lifespan of approximately 99% of the light bulbs?.
Ranking of journals in a category according to impact factor
Presence or absence of infection
Height
b) You construct a survey and create categories for age what scale is this? Identify one advantage and one disadvantage of measuring the variable in this way.
QUESTION 3 (2 marks)
The lifespan of light bulbs is normally distributed with a mean life of 850 hours and a standard deviation of 20 hours.
a) What would be the expected lifespan of approximately 99% of the light bulbs?
b) What percentage of light bulbs should last for at least 830 hours?
QUESTION 4 (8 marks)
Nursing staff in a surgical ward are interested in acupressure in treating postoperative nausea and vomiting. They decide to carry out a study comparing its effectiveness with that of standard treatment. Patients must consent to the study to be included.
a) Explain the difference between internal and external validity in studies such as this [2 marks] b) Identify 3 threats to internal validity in this study and suggest strategies by which they could be prevented or reduced [6 marks] QUESTION 5 (6 marks)
A class of 30 students received the following marks (expressed as percentages) for their overall assessment.
Student Mark Student Mark Student Mark
Grace 50 Sunil 62 Ahmed 67
Jianxia 76 Louisa 90 Tracey 72
Mark 82 David 72 Lian 62
Herlina 52 Jennifer 54 Abdul 20
James 64 Matilda 69 Melanie 65
Bianca 77 Elise 43 James 59
Mishal 35 Ramon 75 Jehan 67
Nawal 85 Caroline 62 Diana 58
Chris 78 Zara 70 Peter 68
Simon 60 Sunit 56 Rebecca 53
a) Calculate: [3 marks] i) The mean
ii) The median
iii) The mode
b) You wish to know whether there is a difference between the marks obtained by male and female students. How would you examine the association between these two variables? [1 mark] c) What statistical test would you perform to examine the significance of this association? [1 mark] d) You are also interested to know whether there is an association between the marks obtained for this subject and those obtained for another unit which all of the students have taken. To compare the marks you calculate Pearsons correlation coefficient and obtain a result of -0.334. What can you conclude about the relationship between the two sets of marks? [1 mark] QUESTION 6 (3 marks)
The graph below indicates the distribution of the memory test scores of 123 people. What inference can you make about the distribution of scores? [1 mark] c) For this dataset what would be the most appropriate measure of: [2 marks] i) central tendency
ii) dispersion
QUESTION 7 (15 marks)
Julia works in a general medical ward where the majority of patients have intravenous infusions. She is concerned about the incidence of phlebitis around the cannulation site and wonders whether it is related to the type of dressing used to secure the cannula. Currently all cannulae are secured with adhesive tape. After examining a variety of available products Julia and her team decide to try a transparent non-occlusive dressing to see if the incidence of phlebitis is affected.
a) Generate a null hypothesis and an alternate (non-directional) hypothesis for Julias study [2 marks] Null:
Alternate:
Julia and her team commence a study to test this hypothesis. For the first 6 months of the study all enrolled patients have their IV cannulae managed with the standard dressing. The incidence of phlebitis is documented and all other relevant data is collected. For the next six months all enrolled patients have their cannulae managed with the new dressing. The same data is collected as previously.
b) What is the name of this research design? What level of evidence (according to the JBI hierarchy) will it generate? [2 marks] c) What design could be used to provide a higher level of evidence? Why is this second design considered superior? [2 marks] d) Give three (3) reasons why Julias team might have chosen the first design over the second [3 marks] e) For this study identify [2 marks]:
i) the independent variable
ii) the dependent variable
f) How will Julias team examine the association between the independent and dependent variables? [1 mark] g) What statistical test would be appropriate to test the hypothesis? [1 mark] h) The test is performed and the result generated is p=0.004. Interpret the p-value. [1 mark] i) What decision would you expect the researchers to make with respect to the null hypothesis? [1 mark] QUESTION 8 (7 marks)
Researchers are interested in comparing the effectiveness of a non-pharmacological method of managing pain compared with pharmacological management in patients with arthritis. They decide to conduct a systematic review.
What would be the expected lifespan of approximately 99% of the light bulbs?
