Tag Archives: Fun Stuff

They finally did it | Parachute use to prevent death and major trauma when jumping from aircraft

17 Mon Dec 2018

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A randomized controlled trial about parachute use to prevent death and major trauma when jumping from aircraft was finally published by Robert W Yeh in BMJ.

Since 2003 Smiths’ Systematic Review that was unable to identify any randomised controlled trials of parachute intervention and thus concluded that the effectiveness of parachutes had not been subjected to rigorous evaluation by using randomised controlled trials, the world was expecting such a trial.

aviao.jpgThe conclusions: ‘Parachute use did not reduce death or major traumatic injury when jumping from aircraft in the first randomized evaluation of this intervention. However, the trial was only able to enroll participants on small stationary aircraft on the ground, suggesting cautious extrapolation to high altitude jumps. When beliefs regarding the effectiveness of an intervention exist in the community, randomized trials might selectively enroll individuals with a lower perceived likelihood of benefit, thus diminishing the applicability of the results to clinical practice’.

Scientific Publications | Christmas Pearls

13 Thu Dec 2018

Posted by in Class Content, Escrita científica, Must read, Research

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Several journals have developed a tradition of publishing slightly different papers in their December issues. These papers are intended to either make a provocative statement, making us reflect upon unusual topics, or provide unusual examples of scientific topics. I like to call them Christmas Pearls. This year my favorite Christmas Pearls:

“Death is certain, the time is not”: mortality and survival in Game of Thrones

Kaplan-Meier survival analysis with Cox proportional hazard regression modeling was used to quantify survival times and probabilities to identify independent predictors of mortality among ‘important characters’ (n = 330) appearing in Seasons 1 to 7 of Game of Thrones.

Although the statistics are quite sound and the data extensive some remarks are mandatory.

First, resuscitation bias was not considered (e.g. John snow). Neither were white walkers. Not clear what justifies the exclusion of these non-less important characters. From a mixed-methods perspective, white walkers could have participated in a focus group discussion of the results, for example.

Secondly, the effectiveness of wall policies for security purposes is clearly understated.

Finally, the authors conclude:

“There is great potential for preventing violent deaths in the world of Game of Thrones. Stable democratic governments, resilient institutions that deliver public goods, and implementation of evidence-based violence prevention policies can decrease the risk of violent deaths considerably“.

Given that winter is coming this is clearly an unrealistic and utopic worldview of Game of Thrones.

 

Is it time to start using the emoji in biomedical literature?

 

The lack of standardisation in emoji artwork that may cause ambiguity in interpretation is quite disturbing. Also, the emoji based alternatives to the denotation of statistical significance can’t really apprehend the need to consider the enunciation of the null hypothesis for adequate interpretation of P-values. The smiling-face-with-sunglasses_1f60e.png in a Kolmogorov-Smirnov to check distribution assumptions for parametric testing may be actually hiding

crying_emoji_small_classic_round_sticker-r4c998b077b254fe69908fa4ca57ce521_v9waf_8byvr_540.jpg.

table 01

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Research on self-treatment of “writer’s block” – a timeline critical appraisal

05 Fri Oct 2018

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Research on the self-treatment of ‘Writer’s Block’ is vast and diversified. You might enjoy reading these articles, they are a fun and fast read. Please, do pay attention to the notes on them. My critical appraisal on the research about ‘Writter’s Block’ may be found at the end of this post.

1974 – the classical CASE REPORT by Dennis Upper:

  • Upper, Dennis (Fall 1974), “The unsuccessful self-treatment of a case of “writer’s block””, Journal of Applied Behavior Analysis, 7 (3): 497, doi:10.1901/jaba.1974.7-497a PDF Here

1983 – a REPLICATION study is performed by Molloy:

  • Molloy, G. N. (1983). The unsuccessful self-treatment of a case of “writer’s block”: A replication. Perceptual and Motor Skills, 57(2), 566-566. PDF Here

1984 – a new REPLICATION, however it partially failed, by Hermann:

  • Hermann, B. P. (1984). Unsuccessful self-treatment of a case of “writer’s block”: a partial failure to replicate. Perceptual and Motor Skills, 58(2), 350-350. PDF Here

1984 – a first REVIEW OF THE LITERATURE on the topic. Still, it was a narrative literature review, we have to wait until 2014 for the first systematic review and meta-analysis

  • Olson, K. R. (1984). Unsuccessful Self-Treatment of “Writer’s Block”: A Review of the Literature. Perceptual and Motor Skills, 59(1), 158–158. doi:10.2466/pms.1984.59.1.158 PDF Here

1985 – a CLINICAL TRIAL by Skinner:

  • Skinner, N. F., Perlini, A. H., Fric, L., Werstine, E. P., & Calla, J. (1985). The Unsuccessful Group-Treatment of “Writer’s Block”. Perceptual and Motor Skills, 61(1), 298-298. PDF Here

1996 – a COHORT study by Skinner:

  • Skinner, N. F., & Perlini, A. H. (1996). The unsuccessful group treatment of “writer’s block”: a ten-year follow-up. Perceptual and motor skills, 82(1), 138-138. PDF Here

2007 – a MULTICENTER REPLICATION study, an attempt to address statistical power issues by Didden:

  • Didden, R., Sigafoos, J., O’Reilly, M. F., Lancioni, G. E., & Sturmey, P. (2007). A multisite cross‐cultural replication of upper’s (1974) unsuccessful self‐treatment of writer’s block. Journal of applied behavior analysis, 40(4), 773-773. PDF Here

2014 – an evidence synthesis in a META-ANALYSIS by McLean:

  • McLean, D. C., & Thomas, B. R. (2014). Unsuccessful treatments of “Writer’s Block”: a meta-analysis. Psychological reports, 115(1), 276-278. PDF Here
Captura de ecrã 2018-10-05, às 16.11.03

McLean, D. C., & Thomas, B. R. (2014). Unsuccessful treatments of “Writer’s Block”: a meta-analysis. Psychological reports, 115(1), 276-278

 

After systematic and iterative readings on the ‘Writer’s Block’ scientific literature my critical appraisal is

 

 

If you have updates on this topic, please let me know

Acknowlegements: to Professor Pedro Lopes dos Santos and Professor Isabel Menezes for sharing with me several ideas on “Writer’s Block” and useful literature about it. I would like to say to them tha

 

 

 

Correlação e causalidade

13 Fri Jan 2017

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Nunca é demais lembrar – correlação não implica causalidade. A correlação é uma medida da intensidade (e do sentido) da associação linear entre duas variáveis e não implica causalidade. Muitas variáveis têm variações semelhantes e, por isso, o valor do coeficiente de correlação é bastante elevado. Veja-se o exemplo da variação do consumo de queijo e a variação do número de pessoas que morreram presas nos lençois da cama nos EUA entre 2000 e 2009: r= 0.947.

chart

Este é um valor com significado estatístico (forte associação linear positiva), mas sem significado prático. Quem quiser pode descobrir aqui novas e interessantes correlações. No estudo da causalidade a correlação está muitas vezes presente, mas não é a correlação que assume a causalidade. De forma resumida, a causalidade é uma inferência sustentada: na definição conceptual (teoria), no controlo de variáveis (metodologia) e na replicabilidade da demonstração de existência de relação entre variáveis (estatística).

Retrospective observational study of Santa Claus

31 Sat Dec 2016

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Dear Santa

Objective: To determine which factors influence whether Santa Claus will visit children in hospital on Christmas Day.

Design: Retrospective observational study.

Setting: Paediatric wards in England, Northern Ireland, Scotland, and Wales.

Participants: 186 members of staff who worked on the paediatric wards (n=186) during Christmas 2015.

Main outcome measures: Presence or absence of Santa Claus on the paediatric ward during Christmas 2015. This was correlated with rates of absenteeism from primary school, conviction rates in young people (aged 10-17 years), distance from hospital to North Pole (closest city or town to the hospital in kilometres, as the reindeer flies), and contextual socioeconomic deprivation (index of multiple deprivation).

Results: Santa Claus visited most of the paediatric wards in all four countries: 89% in England, 100% in Northern Ireland, 93% in Scotland, and 92% in Wales. The odds of him not visiting, however, were significantly higher for paediatric wards in areas of higher socioeconomic deprivation in England (odds ratio 1.31 (95% confidence interval 1.04 to 1.71) in England, 1.23 (1.00 to 1.54) in the UK). In contrast, there was no correlation with school absenteeism, conviction rates, or distance to the North Pole.

Conclusion: The results of this study dispel the traditional belief that Santa Claus rewards children based on how nice or naughty they have been in the previous year. Santa Claus is less likely to visit children in hospitals in the most deprived areas. Potential solutions include a review of Santa’s contract or employment of local Santas in poorly represented regions.

 

Park J, Coumbe B, Park E, Tse G, Subramanian S, Chen J. Dispelling the nice or naughty myth: retrospective observational study of Santa Claus. BMJ. 2016;:i6355.

Full text: Here

 

 

 

‘Beauty is in the eye of the beer holder’: People who think they are drunk also think they are attractive

19 Sat Nov 2016

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Abstract

This research examines the role of alcohol consumption on self-perceived attractiveness. Study 1, carried out in a barroom (N= 19), showed that the more alcoholic drinks customers consumed, the more attractive they thought they were. In Study 2, 94 non-student participants in a bogus taste-test study were given either an alcoholic beverage (target BAL [blood alcohol level]= 0.10 g/100 ml) or a non-alcoholic beverage, with half of each group believing they had consumed alcohol and half believing they had not (balanced placebo design). After consuming beverages, they delivered a speech and rated how attractive, bright, original, and funny they thought they were. The speeches were videotaped and rated by 22 independent judges. Results showed that participants who thought they had consumed alcohol gave themselves more positive self-evaluations. However, ratings from independent judges showed that this boost in self-evaluation was unrelated to actual performance.

Bègue, L., Bushman, B., Zerhouni, O., Subra, B. and Ourabah, M. (2012). ‘Beauty is in the eye of the beer holder’: People who think they are drunk also think they are attractive. British Journal of Psychology, 104(2), pp.225-234.

More – Click Here

 

Yes Sir, no Sir, not much difference Sir.

10 Sat Sep 2016

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Abstract

OBJECTIVE:

To assess whether making the sender’s knighthood explicit in a series of letters would have any detectable effect on the response.

DESIGN:

A random sequence was generated by flipping a coin to determine whether a letter would have ‘Sir Iain Chalmers’ or ‘Iain Chalmers’ typed under the signature. This sequence was prepared independently of the preparation of an alphabetic list of the intended recipients and was then used to determine which letter would be sent. The allocation could not be influenced by prior knowledge of the recipient. Two batches of letters were sent.

SETTING:

Medical royal colleges and associated faculties, and postgraduate medical and dental schools in the UK.

PARTICIPANTS:

Presidents and deans of medical royal colleges and deans of postgraduate medical and dental schools in the UK.

MAIN OUTCOME MEASURES:

Rates of response and the mean number of days between the posting of the original letter and the date on the response.

RESULTS:

No differences between the groups were detected in the response rates: 91% and 90% for ‘Sir Iain Chalmers’ and ‘Iain Chalmers’ (relative rate for response of 1.01, 95%CI 0.83-1.23, P = 0.92), or in the mean number of days to response (‘Sir’: 32 days; ‘no Sir’: 33 days).

CONCLUSIONS:

This finding is consistent with a systematic review of responses to postal surveys, in which the effect of the status of the signatory was investigated. Combining our result with the two trials that are most comparable to our study, in which letters from professors were compared with letters from students, gives a relative response rate of 1.00 (95% CI 0.91-1.10, P = 0.99). There is, therefore, no evidence from the existing randomized experiments that the status of the signatory has any impact on the likelihood or promptness of response-even if the status was conferred by the British monarch.

Clarke, M., Clarke, L., & Clarke, T. (2007). Yes Sir, no Sir, not much difference Sir. Journal Of The Royal Society Of Medicine, 100(12), 571-572. http://dx.doi.org/10.1258/jrsm.100.12.571

Full text – click here