Monday, November 10

Monday, November 10

Evaluating scientific arguments: to generate content, revise content, and review peers’ position papers

IPHY 3700 Writing Process Map

Process: Evaluating Written Arguments

1. Determine whether what you're reading is a scientific argument. If so, parse the key elements of the argument: claims, qualifiers, lines of support, warrants, counterarguments, and limitations.

2. Raise key diagnostic questions for identifying strengths and weaknesses in scientific arguments.

3. Answer the diagnostic questions by applying the think-ahead and think-through strategies.

4. Apply your evaluation of the argument to generate content, revise content, or review a peer's paper.

Step 1: Determine whether what you're reading is a scientific argument—if so, parse the key elements of the argument’s structure

Osteoarthritis is defined on x-rays by osteophyte formation, sclerosis of subchondral bone, cyst formation, and joint space narrowing (15). There are known inconsistencies between findings on x-ray films and clinical symptoms, with only 25 % to 30 % of subjects with osteoarthritis by x-ray being clinically symptomatic (16). Overall, we found few differences except in bone density, which was strongly associated with running in both sexes. Female runners tended to show more sclerosis and spur formation in knees and spine, but the cartilage width in the knees and spine, measured as joint space narrowing, was not different in the two groups. We cannot exclude the possibility that increased bone density resulted in increased ability to "read" sclerosis and new bone formation (spurs) in the running group.

Previous studies of runners and osteoarthritis have shown that the incidence of x-ray evidence of osteoarthritis of the hip is lower in former athletes (mean age, 56 years) who have run for an average of 21 years than in a sedentary control group (17). In a study of 299 subjects with x-ray evidence of hip osteoarthritis, only 10% had ever taken part in any form of sport (18). On the other hand, in a study of 20 runners with knee pain, six had osteoarthritis by x-ray; trauma to the knee or underlying deformity (ligamentous laxity, history of severe trauma) was found to be significantly associated with degenerative changes (19). In addition, ballet dancers are reported to have x-ray evidence of osteophytes without joint space narrowing at the first metatarsophalangeal joint, but only rarely to have symptoms (20).

One theory of the development of osteoarthritis is that joints "wear out" by repetitive impulse loading (21). This impulse loading results in microfracture, then bone remodeling and sclerosis, and stiffened bone. This rigidity increases stress on articular cartilage, with subsequent cartilage breakdown and joint degeneration. It has been observed that total paralysis severely reduces interarticular stress and appears to spare joints from further degeneration. Other authors suggest that it requires both impulse loading and a mechanical derangement to the joint to result in osteoarthritis (22,23). A careful review by Hadler (24) emphasizes that the postulated relationship of osteoarthritis and heavy work rests on almost entirely on anecdotal evidence.Lane et al.

Key Diagnostic Questions for Evaluating Scientific Arguments

1. How relevant are the lines of support for claims?

2. How strong (convincing) are the data-driven lines of support for the claim?

3. How strong (convincing) are the concept-driven lines of support for the claim?

4. How strong is the author's response to counterarguments?

Answer the key diagnostic questions for evaluating scientific arguments, using the think-ahead and think-through strategies

Diagnostic question: How relevant are the lines of support for claims?

•In data-driven lines of support, are the dependent measures valid indicators of what the researchers intended to study?

Marti et al.

Study Subjects Design Independent Variables

Dependent Variables

Results

Marti et al. Runners: Members of Swiss National Team; n=27 men; mean age 27 at start of study; 73 mls/kg/minControls: healthy untrained men; n=23; mean age 20 at start of study

Longitudinal: over a 15-year period1973: Subjects completed running and medical questionnaire 1988: Subjects completed running and medical questionnaire and were given x-ray of hips

Mean total miles run: 97 km per week for runners

Index of severity of sclerosis, bone spurs, joint space narrowing, and pain

Reported as # of subjects affected

Sclerosis:Runners: 16Controls: 3

Spurs:Runners: 8Controls: 0

Narrowing:Runners: 4Controls: 0

Pain:Runners: 8Controls: 0


Hartig and Henderson

Diagnostic question: How relevant are the lines of support for claims?

•In data-driven lines of support, are the dependent measures valid indicators of what the researchers intended to study?


Diagnostic question: How relevant are the lines of support for claims in arguments on your

issues?


Diagnostic Question: How strong are the data-driven lines of support for the claim?

•Is there a critical mass of data to convince readers?

•To what degree are the data statistically significant?

•To what degree are the data practically significant?


Diagnostic question: Is there a critical mass of research data to convince readers?

Previous studies of runners and osteoarthritis have shown that the incidence of x-ray evidence of osteoarthritis of the hip is lower in former athletes (mean age, 56 years) who have run for an average of 21 years than in a sedentary control group (17). In a study of 299 subjects with x-ray evidence of hip osteoarthritis, only 10% had ever taken part in any form of sport (18). On the other hand, in a study of 20 runners with knee pain, six had osteoarthritis by x-ray; trauma to the knee or underlying deformity (ligamentous laxity, history of severe trauma) was found to be significantly associated with degenerative changes (19). In addition, ballet dancers are reported to have x-ray evidence of osteophytes without joint space narrowing at the first metatarsophalangeal joint, but only rarely to have symptoms (20).

Lane et al.


Diagnostic Question: How strong are the data-driven lines of support for the claim?

•To what degree are the data statistically significant?

•To what degree are the data practically significant?

Study Subjects Design Independent Variables

Dependent Variables

Results

Marti et al. Runners: Members of Swiss National Team; n=27 men; mean age 27 at start of study; 73 mls/kg/minControls: healthy untrained men; n=23; mean age 20 at start of study

Longitudinal: over a 15-year period1973: Subjects completed running and medical questionnaire 1988: Subjects completed running and medical questionnaire and were given x-ray of hips

Mean total miles run: 97 km per week for runners

Index of severity of sclerosis, bone spurs, joint space narrowing, and pain

Reported as # of subjects affected

Sclerosis:Runners: 16Controls: 3

Spurs:Runners: 8Controls: 0

Narrowing:Runners: 4Controls: 0

Pain:Runners: 8Controls: 0

Marti et al.


Diagnostic Question: How strong are the concept-driven lines of support for the claim?

-- To what extent does the author's conceptual support fit into the framework of current knowledge in the research field?

-- Has the author presented convincing documentation that leading scientists in the field agree with the conceptual support? -- Does any research exist to confirm the conceptual support?

-- Is the conceptual support logical—that is, are you convinced by the author’s reasoning?

-- To what extent has the author presented sufficient details and depth of explanation in the conceptual support?


Diagnostic Question: How strong are the concept-driven lines of support for the claim?

Osteoarthritis is defined on x-rays by osteophyte formation, sclerosis of subchondral bone, cyst formation, and joint space narrowing (15). There are known inconsistencies between findings on x-ray films and clinical symptoms, with only 25 % to 30 % of subjects with osteoarthritis by x-ray being clinically symptomatic (16). Overall, we found few differences except in bone density, which was strongly associated with running in both sexes. Female runners tended to show more sclerosis and spur formation in knees and spine, but the cartilage width in the knees and spine, measured as joint space narrowing, was not different in the two groups. We cannot exclude the possibility that increased bone density resulted in increased ability to "read" sclerosis and new bone formation (spurs) in the running group.

Lane et al.'s Results Lane et al.'s Discussion

Generating Content through Evaluating Arguments: My Draft

Lane et al. argued that extreme amounts of running do not increase the risk for osteoarthritis. Some data from this study do indeed support the researchers' claim. For example, for men and women, no differences existed between runners and nonrunners in joint space width, which is a valid measure of osteoarthritis. However, Lane et al. present other data and reasoning that fail to support their claim. The women runners had more severe indices of knee joint sclerosis and bone spurs (6.7 and 8.4, respectively) compared to their non-running counterparts (5.1 and 5.1, respectively). Because sclerosis and bone spurs are valid measures of osteoarthritis, these results indicate a greater risks for developing the disease in women runners versus normally active women.

To support their view that the greater incidence of sclerosis and bone spurs does not reflect greater risk for osteoarthritis, Lane et al. argued that the results were simply an artifact of the greater bone density in the women runners. Because the runners had 40 percent more bone mass than the nonrunners, Lane et al. argued that the runners' x-rays were "easier to read" and therefore that the bone spurs and sclerosis were easier to detect. Two problems limit this reasoning. First, regardless of whether the runners' x-rays were easier to read, they still had more severe incidences of bone spurs and sclerosis. Second, Lane et al. overlooked the fact that the men runners also had greater bone density than their nonrunning counterparts. Thus, by the reasoning of Lane et al., the men runners should have had easier x-rays to read and a greater incidence of bone spurs and sclerosis. However, no significant differences existed between the men runners and nonrunners for these measures. Thus, I would argue that the results of this study support the claim that, at least for women, long-distance running increases the risk for developing osteoarthritis.

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Monday, November 10