ghlcom.com

  • Increase font size
  • Default font size
  • Decrease font size
Home Science Good Science
Good Science

What Is Good Science?

E-mail Print PDF

The world has become so much smaller with the advent of the internet.  We can find out what is going on all over the world.  But the problem is that there is so much data and information available it is hard to sort through it all and figure out what is correct and what is not.  You can find opinions and ideas on all sides of just about any subject.

As a researcher you have to look to the science to determine what is really true.  But after looking around a bit, you discover that the science is all over the place as well.  So, then you have to really dig in and find which science was done well and which was done poorly.

Here are the things to look for to help determine if a particular study is "Good Science".

  • Now, this may seem counter-intuitive in this day and age; the study must have a broad scope.  This does not mean that a study can't look into minute details, but if it does so, it must relate those details back out to the big picture.  The more scientific disciplines it agrees with, the better.
  • The conclusion must flow naturally from the methods and the data.  The conclusion should not be a surprise after looking at the data and the methods used to arrive at that data.
  • Basic assumptions made in the study must be considered and analyzed for possibility of error.
  • Good scientific studies always point out their weaknesses and drawbacks, and make suggestions for further studies to be done that could help to clarify the outcomes.
  • Good science is never purely mathematical.  If must be grounded in physical reality.  Can it be related back to, and be in harmony with, actual physical lab work?  This is important.
  • Does the study take into account and analyze previously known studies that may disagree with the outcome of the current study, and explain why the previous studies may have been wrong?
  • Does the study help to further explain and justify things that were already previously accepted, deduced, or discovered? It doesn't have to, but if it disagrees with previously accepted ideas, does it have good explanations for doing so?  Is it strong enough evidence to overcome previous deductions?

Studies that stand up to this type of scrutiny can reasonably be relied upon to have some validity.

Remember that no science is perfect.  Science is simply man's attempt to explain and understand the world around us.  But since it is done from man's intellect, and all men make mistakes, it can never be perfect.

One of the fun things about science is that the more we learn, the more we realize we don't know.

 

 

Last Updated on Thursday, 04 November 2010 17:46
 

Pets and Allergies

E-mail Print PDF

“Having a pet in the house during the first year of a child's life could halve the risk of them becoming allergic to the animals, a study suggests,” reported the Daily Mail.

This story is based on a study that followed 566 children from birth up to the age of 18 years. It found that exposure to a cat in the first year of life was associated with a halved risk of having an immune system that was sensitised to cat allergens. The findings for dogs were more complicated, with the link between exposure and reduced risk of later sensitisation found in boys only.

This study used an appropriate design for investigating the link, but it also have some limitations that make it difficult to conclusively state that childhood pet exposure reduces the later risk of allergies. Only about half of those eligible participated, and the numbers analysed were relatively small. The way the researchers did their analyses also made it difficult to assess whether other factors might be influencing the results.

Although the results of this study are not conclusive, they do suggest that early childhood exposure to a dog or cat is not likely to make a person more allergic to these animals as an adult. However, much larger studies will be needed to confirm the findings.

This study suggests that having a cat in the first year of life may reduce allergic sensitivity to cats at age 18. The results for dogs are less clear. The study used an appropriate study design for addressing this question, but there are several limitations that need to be taken into account when interpreting its results:
  • Less than half of the offspring from the 1,194 eligible pregnancies were included in the final analyses. The results may have been different if all offspring had been followed up.
  • The number of individuals analysed was relatively small. Studies in larger samples of people will be needed to confirm the results.
  • The study relied on mothers and children to report parental allergies, and on teens to recall pet exposure from age six to 18 years. These reports may have some inaccuracies.
  • The researchers carried out separate analyses for offspring with and without a parental history of allergy, but this did not have to be specifically a dog or cat allergy. Homes where parents had a cat or dog allergy might have been less likely to have a pet, and this could influence the results, particularly if a tendency to have allergies is to some extent inherited.
  • As with all studies of this type, there may be some unknown or unmeasured factors that may be influencing results. The study did not directly take into account in the analyses the factors that might influence results, such as parental allergy. Instead, the researchers repeated the analyses in different subgroups of people to see if they found different effects. This makes it difficult to know whether the links found would still be significant if these factors were taken into account.

Although the results of this study are not conclusive, they suggest that early childhood exposure to a dog or cat is not likely to make a person more allergic to these animals as an adult. Much larger studies will be needed to confirm this finding.

 

 

Links To The Headlines

How to beat pet allergy: A cat or dog at home could halve risk. Daily Mail, June 14 2011

 

 

Links To Science

Wegienka G, Johnson CC, Havstad S, et al. Lifetime dog and cat exposure and dog- and cat-specific sensitization at age 18 years. Clinical and Experimental Allergy 2011; 41: 979–986

 

 

Most Allergies Are Caused by This : Click Here.

 

Boost Health Naturally

Straight Forward Weight Loss Made Easy : Learn now -> The Diet Solution Program Click Here!
Have a great day!
Last Updated on Saturday, 23 July 2011 17:19
 

Mother's sleeping position and risk of stillbirth

E-mail Print PDF

 

Widespread media coverage has been given to a study on the risk of stillbirth and the sleeping position of the mother. “Mums-to-be should sleep on their left side”, reported The Mirror. The Daily Mail, said that “women who sleep on their right side or back during the late stages of pregnancy could be at higher risk of stillbirth.”

This news story comes from a study that compared sleeping position and other sleep behaviours in 155 women who had stillborn babies with 310 women who had live births. From these women, the researchers calculated that in high-income countries stillbirth will occur at a background rate of about 3.09 per 1000 births. If women slept on their right side or their back in late pregnancy this risk was 3.93 per 1000, compared to 1.96 per 1000 if they slept on their left side.

These observations are plausible, but this is a small study with several limitations and it can only show an association between sleeping position and stillbirth. It cannot conclusively prove that a woman’s sleeping position affects the risk of stillbirth. This study alone does not provide sufficient evidence to promote an ideal sleep position for pregnant women. This is confirmed by the accompanying editorial, which states: “A forceful campaign urging pregnant women to sleep on their left side is not yet warranted. Further research is needed before the link between maternal sleep position and risk of stillbirth can be regarded as strongly supported.”

It is also important to note that the risk of stillbirth is generally low, regardless of sleeping position.
Pregnant women should speak to their midwives or GPs if they are concerned.

 

Where did the story come from?

The study was carried out by researchers from the University of Auckand and the Wellington Medical School in New Zealand. It was published in the peer-reviewed British Medical Journal.

The research was funded by Cure Kids, the Nurture Foundation and the Auckland District Health Board Trust Fund.

The Independent and The Guardian both reported that the results were preliminary and that the absolute risks were low. However, many newspaper headlines imply that a causal association between sleep position and stillbirth has been conclusively found, and this is not the case. There are numerous inherent limitations to this research, including the high potential for recall bias, which are discussed below.

 

What kind of research was this?

This case control study aimed to determine whether snoring, sleep position and other sleep practices in pregnant women were associated with the risk of late stillbirth. The research was carried out in a population of pregnant women in Auckland. The researchers compared the circumstances of women who gave birth to a stillborn baby at or after 28 weeks of pregnancy (cases) and women who were pregnant at the same time and went on to have a live birth (controls).

Women who gave birth to a stillborn baby were identified from maternity units in the Auckland region. The controls were selected from the districts’ pregnancy registration lists, and two controls in the same week of pregnancy were matched to each case. The study did not include women who were pregnant with more than one baby, those whose baby had a congenital abnormality, or those who were registered outside Auckland.

The researchers say that previous studies have found that sleeping on the back is associated with a disruption in normal breathing patterns. They also say that lying flat on the back during late pregnancy can reduce the mother’s cardiac output (the amount of blood pumped out from the heart with each heartbeat). This is because the major veins in the body that return blood to the heart (the vena cavae) are positioned just to the right side of the center of the body. As such, it is possible that in heavily pregnant women, the pressure of the baby when lying flat or just to the right could interrupt the return of blood to the heart. This could reduce the mother’s cardiac output and, in turn, affect blood supply to the uterus and placenta.

For this reason, women having a caesarean section are normally positioned lying tilted towards their left to take pressure off the vena cavae. However, there has been no research into whether maternal sleep position and other sleep-related factors affect the risk of late stillbirth.

The researchers’ theory was that both sleep-disordered breathing and lying on the back would be associated with increased risk of stillbirth late in pregnancy.

 

What did the research involve?

Researchers interviewed women during the few weeks after stillbirth, asking them about their sleeping habits and factors that can affect the risk of stillbirth. They used self-reported snoring and daytime sleepiness as substitutes for sleep-disordered breathing, as there is no validated tool for assessing sleep-disordered breathing during pregnancy.

The women were also asked about their sleep position (either left side, right side, back or other) before the pregnancy, during the last month, during the last week and during the last night of pregnancy. They were also asked about their daytime sleep patterns during the last month, and how often they got up during the night. Data were also collected on factors that previous studies have suggested are associated with increased risk of stillbirth. These included maternal age, ethnicity, number of previous full-term pregnancies, smoking status, body mass index and level of social deprivation.

The interviews of the cases occurred on average 25 days after the date of the stillbirth. All factors were analysed independently to detect any association with stillbirth. The control women were interviewed about their sleep patterns the previous night, and other factors, at the same time-point in their pregnancy as their matched case had experienced the stillbirth (e.g. if a case experienced a stillbirth at 30 weeks, her matched control would be interviewed when she was 30 weeks pregnant, i.e. before she had had her baby).

The researchers then carried out analyses on the maternal factors that were associated with stillbirth, taking into account any that had been identified as increasing the risk of stillbirth.

 

What were the basic results?

The main findings of the research were:

  • Compared to sleeping on the left side, sleeping on the right side was not significantly associated with increased risk of stillbirth.
  • Compared to sleeping on the left side, sleeping on the back and in other positions was associated with an increased risk (2.54 and 2.32 times as likely to have a stillbirth respectively).
  • Women who got up to go to the toilet once or not at all during the last night of pregnancy were 2.42 times as likely to experience stillbirth as those who got up more.
  • Women who reported regularly sleeping during the day in the last month of pregnancy were 2.04 times as likely to experience stillbirth as those who didn’t.
  • Duration of sleep at night during the last night of pregnancy had no significant effect on risk.
  • There was no observed association between snoring and risk of stillbirth.

The researchers point out that the absolute risk of late-term stillbirth in high-income countries is low (3.09 per 1,000 births in the study population), and non-left-side sleeping only slightly increased this risk (to approximately 3.93 per 1,000 births).

 

How did the researchers interpret the results?

The researchers concluded that their preliminary study has produced findings that “require urgent confirmation in further studies”. They say that they have identified a potentially modifiable risk factor for stillbirth, but acknowledge both the strengths and limitations of their study.

 

Conclusion

This study found that not sleeping on the left side during the last night of pregnancy was associated with a higher risk of stillbirth.

The researchers used an appropriate study design to investigate their theory. A case control study such as this is useful for looking at outcomes that are relatively rare, such as stillbirth. The participants were also carefully selected and well matched, which improves the chances that these findings can be applied to the wider population of pregnant women. However, the study had several limitations that must be considered when interpreting its finding, and which the researchers acknowledge:

  • The results may be subject to several biases. For example, the women may not have accurately recalled their sleeping position, which is difficult to confirm. As the researchers say, there is currently no validated method for assessing sleep-disordered breathing or sleep pattern during pregnancy. This limitation is partly alleviated by the fact that most participants used reference points for their sleep position, such as “I always faced away from the door” or “I slept facing my husband”.
  • It’s also possible that the women who had stillborn babies may have misremembered the events leading up to delivery as they sought to find a reason for the trauma they had been through.
  • There was also a time gap between when the cases and controls were asked to report their sleeping pattern. Cases were asked about sleep position on average 25 days after their last night of pregnancy, whereas controls were asked to report on the previous night’s sleep position.
  • It is also possible that the observed association is an example of reverse causality. In other words, this study cannot determine whether the association between sleeping position and stillbirth is due to sleep position increasing the risk of stillbirth, or stillbirth resulting in changed sleep patterns. The last night of pregnancy before stillbirth was examined but, as the researchers point out, the last night of pregnancy may not have been the night before the foetus died, which may have died before this time. This may have altered the results. For example, if the foetus had already died, absent foetal movements could have influenced the mother’s choice of sleep position, or reduced the number of times she got up during the night because she had less disturbance to her sleep. Therefore, sleep position and reduced frequency of getting up during the night may have been a result of foetal death, rather than a risk factor for it.
  • Finally, it is possible that an unknown factor is associated with both sleep behaviour and stillbirth and which accounts for the observed relationship.

The observations of this study are plausible. However, the study was small and can only detect associations, rather than conclusively proving that sleeping position affects the risk of stillbirth. This study alone does not provide sufficient evidence to support widespread campaigns promoting an ideal sleep position for pregnant women. This is confirmed by the editorial that accompanies the study’s findings, which says: “A forceful campaign urging pregnant women to sleep on their left side is not yet warranted. Further research is needed before the link between maternal sleep position and risk of stillbirth can be regarded as strongly supported.”

It is also important to note that the risk of stillbirth is quite low, regardless of sleeping position. The researchers calculated that in a high income country, stillbirth occurs at a background rate of 3.09 per 1000. Sleeping in any position other than the left side (e.g. back or right side) resulted in a risk of 3.93 per 1000, while sleeping on the left side they calculated would result in a risk of 1.96 per 1000.

Though this study cannot conclusively prove that sleep pattern affects the risk of stillbirth, these findings require further investigation. Future research should attempt to address some of the potential limitations of this study. Further research would also benefit from a validated method of measuring sleep-disturbance breathing in pregnant women.

Pregnant women should speak to their midwives or GPs if they are concerned.

 

 

Links To The Headlines

Sleep position during pregnancy 'link to still-birth'. BBC News, June 15 2011

Sleeping on your right side 'could put your unborn baby at risk'. Daily Mail, June 15 2011

‘Sleep on your left to avoid stillbirth’. The Sun, June 15 2011

Mums-to-be should sleep on their left side. Daily Mirror, June 15 2011

Sleeping on left may cut risk of stillbirth. The Independent, June 15 2011

Link found between stillbirth and sleeping position in pregnancy. The Guardian, June 15 2011

 

 

Links To Science

Stacey T,  Thompson JMD, Mitchell EA, et al. Association between maternal sleep practices and risk of late stillbirth: a case-control study. BMJ 2011; 342: d3403

Chappell LC, Smith GCS. Should pregnant women sleep on their left? BMJ 2011; 342:d3659 (Editorial)

 

 

Boost Health Naturally

There is a tonic that balances all the major systems of the body.  It was formulated using only tonic (meaning balancing) herbs.  It was formulated without the use of alcohol or other substances that can destroy the tonicity of the herbs.  Most herbal concoctions are created using alcohol or other chemicals that destroy the balancing abilities of the herbs.  To learn more about this wonderful herbal tonic stay tuned.  We will soon publish a whole article on it.


Straight Forward Weight Loss : Learn now - The Diet Solution Program Click Here!

 

Last Updated on Tuesday, 10 January 2012 19:46
 

Study finds olive oil 'lowers stroke risk'

E-mail Print PDF

Here is another interesting report on olive oil:

“Olive oil staves off stroke in the elderly,” reported The Daily Telegraph. It said that a study has found that a diet rich in olive oil lowers the risk of having a stroke in later life by more than a third.

This study looked at about 8,000 people over 65 and found that those who had plenty of olive oil in their diet had a 41% lower risk of a stroke than those who never used olive oil.

This was a large, well-designed study with a long follow-up period. However, it is not robust evidence that olive oil independently lowers the risk of a stroke, and the findings should be viewed with some caution. Limitations include the fact that the participants reported their olive oil use themselves, and only once at the start of the study raising the possibility that it could have changed over time. Their risk of a stroke may have also been affected by other factors that haven’t been taken into account.

Olive oil is an important constituent of the Mediterranean diet, which is associated with health benefits such as lower risk of heart disease. However, several factors lower the risk of having a stroke, including a healthy balanced diet with low levels of salt and saturated fat, and regular exercise. Adding lots of olive oil to the diet while ignoring these other factors is unlikely to bring benefits.

 

Where did the story come from?

The study was carried out by researchers from the French research centre INSERM and other medical and academic centres in France.

The lead researcher received financial support from Institut Carnot LISA (translated as Lipids for Industry, Safety and Health), an industry-sponsored organisation. Another researcher is a consultant for the food and beverage company Danone. The study was published in the peer-reviewed journal Neurology.

The study was covered accurately but uncritically in the press. The Daily Mail, BBC News, Daily Mirror and Daily Express all included comments from an independent expert.

 

What kind of research was this?

This prospective cohort study investigated whether high olive oil consumption and high levels of oleic acid in blood plasma (a marker of olive oil intake) are associated with lower incidence of stroke in people aged over 65.

The researchers point out that the Mediterranean diet is associated with a lower risk of dying from cardiovascular disease as well as a reduction in risk factors for cardiovascular disease, such as high cholesterol. High olive oil consumption is an important feature of this diet.

They say that higher consumption of olive oil has been associated with a lower risk of heart attacks and deaths from all causes, and has also been linked to lower blood pressure. They say their study is the first to test whether olive oil is associated with a lower risk of strokes, independent of other risk factors.

 

What did the research involve?

The participants were obtained from another, ongoing cohort study investigating vascular risk factors for dementia. This cohort study included 9,294 participants from three cities in France, who were 65 or over when the study began in 1999-2000. They were interviewed by trained psychologists and nurses at the start, and follow-up examinations were carried out at two, four and six years after the first visit, either by face-to-face interviews or through a questionnaire.

This study looked at the effect of olive oil on strokes, so the participants had to have had no history of strokes when they were first enrolled. At each follow-up, the participants were asked if they had had a stroke or stroke symptoms or been admitted to hospital for a stroke. When the answer was positive, the researchers obtained further medical data from the patient’s health services and doctors. Strokes were defined according to the diagnosis of an expert committee.

This study had two parts. The first main analysis investigated whether there was an association between reported olive oil consumption at the start of the study and the risk of a stroke over six years.

At the first interview, researchers collected dietary details from the participants, including type of dietary fats used for dressing, cooking and spreading. They divided olive oil consumption into three categories: no use, moderate use (for cooking or dressing alone) and intensive use (cooking and dressing).

The second, smaller part looked at olive oil consumption and blood levels of oleic acid (a fatty acid that is a biological marker for olive oil consumption) at the start of the study and the risk of a stroke over six years. In a sample of 1,364 people taken from those enrolled in the original study, the researchers recorded blood levels of fatty acids at the start of the study, with results for each fatty acid expressed as a percentage of the total.

Validated statistical methods were used to analyze the findings. The analyses took into account other risk factors for having a stroke, including age, gender, education, diet and physical activity, drug and alcohol use.

 

What were the basic results?

Of the participants in the original study, 7,625 were eligible for the main investigation into olive oil and stroke risk, and 1,245 people were available for the analysis of oleic acid levels and stroke risk.

In the main sample, there were 148 strokes. The researchers found that compared to those who never used olive oil, people who used it intensively had a 41% lower risk of having a stroke (hazard ratio 0.59, 95% confidence interval 0.37 to 0.94). This is a very wide confidence interval and suggests that the true risk of stroke has a high chance of being lowered by somewhere between 6% to 63%.

In the secondary sample of 1,245 people whose blood levels of oleic acid were measured, there were 27 strokes. A higher level of oleic acid in the blood was found to be associated with a lower risk of having a stroke. However, there was a low association between olive oil use and oleic acid measurements. The researchers found that other dietary constituents were associated with higher oleic acid blood levels, including butter, goose and duck fat.

 

How did the researchers interpret the results?

The researchers say their results suggest a “protective role” for high olive oil consumption on the risk of strokes in older people. They suggest that older people should be advised to consume more olive oil.

 

Conclusion

This was a large, well-designed study with a low drop-out rate (most of the participants completed the study). However, it has several limitations that mean its findings should be viewed with caution:

  • The study relied on people to report their own olive oil use, which could introduce a degree of error.
  • The researchers only asked people once about olive oil use at the start of the study. It is possible that people’s consumption of olive oil may have changed over time.
  • The wide confidence intervals in the main analysis raises the possibility the findings were due to chance, or at least that the reduction in risk is less than the 41% quoted by the researchers or the “more than a third” quoted by the papers.
  • There was a very low association between blood measurements of oleic acid and olive oil use. This throws doubt on the use of oleic acid as a marker for olive oil consumption and may further suggest that self-reporting of olive oil consumption itself might be inaccurate.

Olive oil has been associated with several health benefits and, as part of the Mediterranean diet, is of interest to researchers. Being composed of monounsaturated fats (80%) and polyunsaturated fats (20%), it is also a healthy substitute for vegetable fats such as soy, canola, corn oil, etc. However, further research is required before it is known for certain how much olive oil can lower the risk of strokes, independent of other risk factors.

 

 

Links To The Headlines

Olive oil staves off stroke in the elderly. The Daily Telegraph, June 16 2011

Olive oil used in cooking and salads 'cuts risk of stroke by 41%'. Daily Mail, June 16 2011

Olive oil 'can help prevent strokes among over-65s'. Daily Mirror, June 16 2011

Olive oil cuts the risk of a stroke by 40%. Daily Express, June 16 2011

Olive oil 'helps prevent stroke'. BBC News, June 16 2011

 

Links To Science

Samieri C, Féart C, Proust-Lima C, et al. Olive oil consumption, plasma oleic acid, and stroke incidence. Neurology 2011, Published online before print June 15

 

Boost Health Naturally

There is a tonic that balances all the major systems of the body.  It was formulated using only tonic (meaning balancing) herbs.  It was formulated without the use of alcohol or other substances that can destroy the tonicity of the herbs.  Most herbal concoctions are created using alcohol or other chemicals that destroy the balancing abilities of the herbs.  To learn more about this wonderful herbal tonic stay tuned.  We will soon publish a whole article on it.


Straight Forward Weight Loss : Learn now - The Diet Solution Program Click Here!

 

Last Updated on Tuesday, 10 January 2012 20:36
 

Have you tried quilting?

E-mail Print PDF

Perhaps this is a good lifestyle change for you.  There is really no solid conclusions in this study, but you may find it interesting.

"Quilting improves your health in ways even exercise can’t manage,” according to the Daily Mail. The newspaper said that making quilts is “uniquely good for you”.

This news story was based on a small survey that interviewed 29 women who belonged to a quilting group. The survey asked them about the satisfaction they got from quilting. The women, the majority of whom were retired, explained that they felt a sense of satisfaction from the creative process and, in particular, problem solving, working with colours and being able to lose themselves in their work. They also said that they enjoyed the social side of the activity, sharing tips and the inspiration they got from seeing other people’s work.

The research found that these people felt they benefited from their creating activity, but it did not objectively measure health or well-being. While it may inspire people to try this particular activity, it does not necessarily mean that quilting is more likely to have positive psychological effects than any other hobby or exercise. Overall, the design of this small study allows only limited conclusions to be drawn.

Some of the qualitative reports of quilting included:
  • Quilting was an accessible way for participants to be creative, incorporating different colours and textures and work with their hands to produce a tangible product. The women said that this offered a sense of wellbeing that they did not find in their jobs.
  • Participants identified that the use of bright colours had uplifting effects on mood and that this was particularly important in winter.
  • The majority of participants said that they became captivated by the creative process, which they likened to a “flow” - losing themselves in their quilting, displacing their anxieties and relaxing them. Participants said that these psychological benefits continued after they had stopped quilting.
  • The participants said that quilting required problem solving, such as designing new patterns and incorporating shapes. Even those with more years’ experience reported that they continued to find new challenges.
  • The participants reported that quilting was good for keeping busy, developing skills while being able to produce something at the end.
  • The participants appreciated the social side of quilting, and although the majority also made quilts alone, they enjoyed sharing ideas and skills with others. They said that seeing other people’s quilts was an inspiration to develop skills, and that receiving a quilt and receiving praise from others boosted their confidence.
Further research is needed to see whether quilting and other hobbies are good for mood, well-being and health. Ideally, studies in this area would take the form of a randomized control trial, perhaps measuring changes in factors such as blood pressure or well-being scores in groups assigned to try a new hobby, and comparing these changes to people performing no activity.

 

Links To The Headlines

Why quilting improves your health in ways even exercise can't manageDaily Mail, June 13 2011

 

Links To Science

Burt EL, Atkinson J. The relationship between quilting and wellbeing. Journal of Public Health, June 5 2011 (first published online)

 

Boost Health Naturally

Straight Forward Weight Loss : Learn now - The Diet Solution Program Click Here!
Have a great day!
Last Updated on Saturday, 23 July 2011 17:24
 
  • «
  •  Start 
  •  Prev 
  •  1 
  •  2 
  •  Next 
  •  End 
  • »


Page 1 of 2

Login Form

Create an account to leave comments and questions.

Sponsors


Join GHL Email List

If We Have Helped You ...

Amazon Recommendations