Complementi di Informatica Medica a.a. 2009-2010

Rachelle Ta-Min, Jose Arocha, Laurie Hoffman-Goetz - University of Waterloo, Ontario, Canada.

There are a number of advantages to presenting health information online including convenient and easy access to information for patients

Unfortunately, much of the information aimed at educating the general public is not always easy for them to understand.

Rachelle Ta-Min, Jose Arocha, Laurie Hoffman-Goetz

To assess the readability and comprehensibility of web-based cancer information.

Rachelle Ta-Min, Jose Arocha, Laurie Hoffman-Goetz

Currently, readability formulas are the most popular methods for assessing readability of web-based information.

However, although these formulas correlate with reading difficulty, they leave out aspects of text information, such as coherence, that influence the understanding of information.

Proper evaluation of online health information to ensure that it meets the needs of the public requires taking into account both readability and comprehensibility

Rachelle Ta-Min, Jose Arocha, Laurie Hoffman-Goetz

Readability is a judgment of how easy a text is to understand for a given established and characterised population.

Readability can be objectively assessed using readability formulas.

These generate a score usually based on one semantic factor (the length/difficulty of words) and one syntactic factor (the length/difficulty of sentences).

Rachelle Ta-Min, Jose Arocha, Laurie Hoffman-Goetz

Differences in readability, comprehensibility and the ability to form a mental model from text can be appreciated from the 3 sentences below:

i. To improve their prognosis, patients with carcinoma of the breast and no evidence of distal metastases may receive adjunctive radiotherapy in addition to oestrogen-receptor blockade.

ii. Patients with cancer limited to the breast may receive radiotherapy as well as hormone therapy.

iii. Patients with breast cancer may receive X-ray treatment to kill cancer cells.

Rachelle Ta-Min, Jose Arocha, Laurie Hoffman-Goetz

Web pages for breast, prostate and colorectal cancer with low and high readability levels were assessed using readability formulas (Flesch-Kincaid, Flesch Reading Ease, and SMOG –Simple Measure of Gobbledygook) and methods of propositional density (PD) and propositional analysis based on Kintsch’s theory of comprehension.

Websites were selected by typing the keywords “breast cancer”, “prostate cancer” and “colorectal cancer” into each of the ten most popular Internet search engines

Rachelle Ta-Min, Jose Arocha, Laurie Hoffman-Goetz

The web pages were also read by 16 adults and their recall and understanding explored using verbal protocols.

Propositional density (PD) and coherence were measured for the web pages, whereas measures of recall, concepts, inferences, and coherence were measured from the verbal protocols.

Rachelle Ta-Min, Jose Arocha, Laurie Hoffman-Goetz

The main findings of the study were: 1. Propositional density (PD) scores were not

associated with web page semantic difficulty

Rachelle Ta-Min, Jose Arocha, Laurie Hoffman-Goetz

Propositional density and readability scores for breast cancer, colorectal cancer, and prostate cancer at low and high readability levels

2. Readability scores were not consistent across measures

3. Verbal protocols revealed marked individual differences in information recalled, inferences generated, and coherence of participants’ mental models.

Rachelle Ta-Min, Jose Arocha, Laurie Hoffman-Goetz

The lack of association between readability and Propositional density (PD) suggests that the latter is an independent readability marker for web-based information and that standard readability is independent of coherence.

In addition, the lack of agreement among the readability formulas suggests that more than one formula should be used.

Rachelle Ta-Min, Jose Arocha, Laurie Hoffman-Goetz

The findings of the study suggest that using alternative methods of measuring text difficulty to assess coherence and its relationship with readability is necessary.

Further work is required to devise tools and methods that can be used to easily evaluate the readability and comprehensibility of online health information.

Rachelle Ta-Min, Jose Arocha, Laurie Hoffman-Goetz