As mentioned above, a survey seeks to make inferences about a population based on information obtained from the sample. This objective is related to cost and time constraints, because, as in our example of American teenagers, it would be very costly to measure all of their IQs. Instead, a representative subset (a “random sample”) of teenagers is taken, and then their IQs are measured. In some situations, the entire population might be surveyed, as in a census or when dealing with small populations. Even if the population is small, the test to obtain particular information from an element might require that element’s destruction. For example, to determine one’s blood cholesterol level, a blood sample consisting of a few milliliters of blood, not all of it, should be taken. If we want to determine the average lifespan of light bulbs manufactured on an assembly line, we should take a reasonably sized sample, such as a few hundred, and test them to see how long they last. Otherwise the company would go bankrupt.

The basic problem of a survey is the validity and reliability of its results. The solution lies in the three segments of conducting a survey: planning, data collection, and analysis and reporting. Usually the public sees the reporting segment. However, since the public does not know how the survey was conducted, it is prone to be misled by the reported results. To determine a survey’s reliability, one must know the sources of bias affecting its outcome. These biases can be traced to the interviewer or the researcher, the format of the questionnaire or the experiment, the availability of information, and other causes.

From a researcher’s point of view, these source biases must be kept as small as possible. The most serious bias problems arise from the questionnaire type and the sampling methods used. For example, if the questionnaire refers to a socially desirable situation, respondents tend to answer in accordance with the social desirability. Say people are asked whether they read the front page or the sports page of the newspaper first. Many will answer that they read the front page first, even if they really read the sports page first, because reading the front page first makes one look more sophisticated. Hence it is a socially desirable attribute.

A more interesting example is provided by a survey done by the American Society of Microbiology. Its researchers wanted to determine the percentage of people who wash their hands after using public restrooms. When they surveyed a randomly selected sample in the Washington, DC, area over the phone, 94 percent said that they washed their hands afterwards. However, researchers who observed 6,333 people using public restrooms in five major American cities found that only 68 percent did so. Here, the socially desirable situation is, of course, washing one’s hands after using public restrooms.

A researcher also has to be very careful when interpreting the results of a question seeking potentially incriminating or embarrassing (i.e., socially undesirable) information. Suppose we distribute to the people of a particular town a questionnaire asking whether they have used marihuana during the past 12 months. The responses will give a very low estimate of the exact percentage of marihuana users, because drug usage is a serious crime in this country. Fortunately there is an interesting solution to this problem: Randomized Response Technique (RRT).

This is how it works. Suppose that the interviewer presents a 6-sided die to the respondents and gives them a paper that contains the following instructions: Roll the die first, but do not show the outcome to the interviewer. Then:

i) If it shows 1 or 2, answer YES regardless;

ii) If it shows 3 or 4, answer NO regardless;

iii) If it shows 5 or 6, answer truthfully.

Give your answer in the following boxes:

[]Yes []No

By using this clever method, one can estimate the exact percentage more accurately, because there is no way to match the answers to the respondents. Here’s how it can be done: Say we surveyed 1,500 people and received 700 “yes” answers. First, the probability of the die showing 1 or 2 is 2/6 (or 1/3). The odds for the die showing 3 or 4, as well as 5 or 6, are the same. Hence we expect that the die will show 1 or 2 in 500 respondents, 3 or 4 in 500 respondents, and 5 or 6 in 500 respondents. According to the directions, we expect 500 respondents to answer “yes” and another 500 respondents to answer “no” regardless of the truth. If the total “yes” responses is 700, then the number of “truthful yes” responses is 700-500=200. Now, we see that 200 out of 500 answered “yes” when the questionnaire asked for a truthful answer. This result gives 40 percent (=200*100/500) as the estimated percentage of actual marihuana users.

Another source of serious bias stems from the sampling plans and methods employed. In practice, various time, space, and cost constraints prevent us from dealing with actually random samples (samples that are representative of the population). Given this, let’s analyze the most common sampling methods.

Haphazard Sampling: Many biological studies use this method to select specimens to be examined from a cage or a tank. This technique involves catching the animals by hand or by a net “at random” in that particular cage or tank. However, those animals that are caught in such a manner are usually the ones that are more friendly, weaker, or less agile. This problem can be solved with more effort and money. Therefore, when the results of a biological research study are presented, one should check the randomness of the sample and then reach his or her own conclusion, because if the results are the based on haphazard sampling they will be quite biased.

Judgment Sampling: In this method, “a couple of experts” determine the “typical units” that represent the population. This method is also extremely poor, because “experts” tend to disagree on which items are typical. Yates (1981) presents a good example. He had 12 experts collect a total of 1,200 stones, and then asked them to select three distinct samples of 20 stones as typical of the population according to their weight. Surprisingly, 30 out of 36 samples selected overestimated the true average weight.

Volunteer Sampling: If respondents are chosen from volunteers (generally human beings), then the results have considerable bias. This method is widespread in medical studies, because usually it is the only way to get relevant results. Since the medical profession’s ethical code does not allow one to obtain random samples in medical experiments, various animals, such as guinea pigs, are used in labs. However, because drugs that are effective on animals are usually not all that effective on human beings, their relevance is not so clear. For example, we often hear that a particular “study shows that such and such an ingredient is harmful to your health, or cures such and such a disease.” These are very poor statements, and hence not so reliable. However, they were the only results we could obtain. This bias is somewhat removed by continual progress in medicine.

Restrictive Sampling: This method is particularly important, because it yields very strange results when applied to social science research. Here, one takes a sample that is easy to obtain for a couple of different reasons. For instance, in archeology and history, the possessions of a king or an aristocrat are more likely to survive than those of a serf or a vassal, for the belongings of the rich and powerful are more durable and of a much higher quality and therefore survive for a longer time. In the United States, for example, a great deal of furniture and many houses of slave owners have survived; only very little of their slaves’ possessions have survived. In Egypt, the artifacts discovered by archeologists belong mainly to the upper class (pharaohs, the noblility, etc). As a result, historians and archeologists produce very biased results, for their conclusions are based mainly on evidence belonging to members of the rich and/or aristocratic classes.

Is there a solution? Obviously, researchers only accept tangible items as evidence. Even though these artifacts are “hard” evidence, they cause the poor, and those who led modest and humble lives, to be under-represented in history. For example, many Prophets left virtually no personal items behind, except for ones like Muhammad, Jesus, and Moses (peace be upon them all), who were considerably recent.

Such an absence of personal items might be due to the fact that they led modest lives and shunned luxury. Hence, historians and archeologists should reconsider their position on this issue. In order to correct the bias engendered by restricting their conclusions only to tangible evidence, they should add the Holy Books and written religious texts to their category of “acceptable” evidence.

Another example is the media, whose usage of restrictive sampling produces very bigoted and biased results. The image of Islam presented in the Western media is a good example of this, for its depiction of Islam contains many misconceptions. First, Islam is presented as an exclusively Arab religion, despite the fact that Arabs account for only 15 to 20 percent of all Muslims. So either obtaining a representative sample of the world’s 1.2 billion Muslims seems very hard to journalists, or else they deliberately restrict their samples to Arabs.

The most serious and severe misconception, however, is the media’s equating Islam and terrorism, although the word “Islam” literally means “peace.” On the other hand, the Western media somehow manages to mention Muslims and terrorism together many times. This is also quite odd, for only 1 percent or less of the world’s 1.2 billion Muslims favor so-called “militant” groups. When news about such people is broadcast, this little percentage is strangely magnified, and the stereotype is generalized to include all Muslims.

It is also incorrect to label these militant groups as “Islamic.” This is definitely a sampling problem, which seems to be done either on purpose or in a cursory way. Are there no good Muslims among 1.2 billion Muslims of the world? Rationally, if we suppose the impossible (that all Muslims really are terrorists), they would have destroyed the entire world already. Similarly, but to a lesser extent, there are stereotypes for Jews and Christians (mostly Catholics).

There is an urgent need for collaboration and cooperation between different religious groups to get rid off such damaging misconceptions and stereotypes. Muslims, having the worst stereotype, should be in the forefront of this undertaking. According to my experience and knowledge, many religious beliefs and teachings, and their followers, bear no resemblance to these misconceptions.

Such restricted sampling results in many seriously flawed conclusions in social science disciplines. Consider the case of Sigmund Freud, who still has many advocates and fans, as well as opponents, of psychology. From a sampling perspective, his analysis of the ego (psychoanalysis) cannot be considered reliable, for he based his hypothesis on just two persons: himself (at 1897) and an 18-year old female hysteric (Dora). Even from the statistical point of view, two people (the first one probably obsessed with sexuality, and the second an obviously abnormal person) can in no way be considered representative of the 2 billion people living at that particular point in time. Here, of course, I consider the severe time and cost restraints, but still, the existence of such difficulties does not justify the validity of Freud’s conclusions.

CONCLUSION

In this article, we approached different issues in the social and physical sciences from a sampling (statistical) point of view. Surprisingly, this approach gave very interesting results in various sciences. The validity of any survey or research does not depend on its publicity (whether it is published, broadcast, or widely accepted); what is essential is that the whole picture be covered. Newly emerging interdisciplinary areas can help keep track of the whole picture. Also, the validity and reliability of results obtained through research, surveys, hypotheses, and theories depend upon the researcher’s morals and honesty and ability to see “the big picture.” Scientists and journalists should be very careful and responsible in their research, for most people are inclined to accept, without further exploration, whatever they hear or read.

REFERENCES

• Bill, James A. “Islam: Misunderstood throughout the World.”
• http://www.muslim.net/isla /intro8.html.
• Freud, Sigmund. “Chronology.” http://freud.t0.or.at/ freud/index-e.htm.
• “Misconceptions about Islam.”
• http://www.muslim.net! islam/miscons.html.
• Warde, William D. Sampling Methods. Oklahoma State University, 1990.

There are many reasons why a developing baby may have congenital problems (Moore, 1989, p.lO8). Exposure to infections and certain drugs (most commonly, alcohol), chromosomal abnormalities and inherited congenital conditions have all been shown to disrupt normal fetal development. In this article we will concentrate on the diagnosis of chromosomal and genetic disorders during pregnancy.

PNT procedures and their interpretation can be extremely intimidating for parents. It is therefore important that tests are done only after a full explanation of the procedures involved and their possible consequences. The aim of PNT is to inform and prepare parents for the birth of an affected infant, so that they can choose between the possible courses of action (Aksoy, 1996). The possibilities will include: (1) in utero treatment; (2) delivery at a special centre for immediate postnatal treatment; and 3) termination of an affected fetus, i.e. abortion.

Over the years, professional standards and laws have evolved which influence the clinical application of PNT and help to tackle many of the complex ethical issues involved. There is little doubt that relatively non-invasive techniques whose primary purpose is to diagnose treatable disorders and then treat them, before or after birth, would be warmly welcomed by all, especially the parents. The fact is, however, that in practice PNT is generally being used to diagnose abnormality and then terminate the life of the unborn babies. The reality is that prenatal diagnosis rarely leads to fetal therapy

In what follows, we will try to explain the range of prenatal tests available and indications for their appropriate use. We will consider some of the technological advances on the horizon in this field of medicine, as well as some of the ethical dilemmas that arise.

Prenatal Diagnostic Tests

Prenatal diagnostic tests can be divided into two types, invasive and non-invasive. Non-invasive tests simply involve a blood sample taken from the pregnant woman or an ultrasound scan. Invasive tests on the other hand are more complicated and involve obtaining a sample of cells or tissue from the developing foetus, either by amniocentesis or chorionic villus biopsy. The samples obtained by invasive tests can be used, specifically to assess the fetal chromosome pattern, to determine if the fetus has a particular genetic mutation, or for a whole range of biochemical assays.

Maternal Blood Sampling. Between 15 and 19 weeks of pregnancy, the pregnant woman attending ante-natal clinic will be offered a blood test. The blood sample will be analysed to assess the level of three proteins, b human chorionic gonadotropin (b HCG), oestriol and a -fetoprotein (a FR). The three levels in combination with the mother’s age can be used to estimate the risk of the baby being affected by a chromosomal problem, especially Down’s syndrome (Wald and Cuckle, 1992, pS63). If the test result indicates a high level of risk, the mother will be offered further tests to assess the status of her baby.

Ultrasound Scan. Ultrasound uses high frequency waves to form a picture as the waves are reflected back by tissues of different density. The developing fetus grows in a liquid filled sac (amnion). As fluid shows black on the scan, this provides a good contrast with the fetal parts allowing high resolution images. Early in the first trimester an ultrasound scan can be used assess the viability of a fetus and to estimate its stage of development. Most women will be offered a formal high resolution scan at between 16 and 19 weeks (Sutton, 1990, pp.20- 1). The images from the scan will be the first time the expectant mothers see the baby. For many, this is a happy event; for the others it could be a very sad event if the scan indicates an abnormality.

Amniocentesis. In this test, done between 15 and 20 weeks of pregnancy (Cohen, 1990, pp.19- 20), a very fine needle is passed through the abdomen under ultrasound guidance, avoiding the fetus, and a sample of amniotic fluid containing fetal cells is withdrawn. The sample is cultured to grow more cells so that the chromosome pattern of the cells can be examined or DNA extracted for genetic analysis. This process can take three weeks, a period of considerable anxiety for the parents. There is also a small risk of miscarriage occurring after an amniocentesis.

Chorionic Villus Sampling. In this test, done in the same way as than amniocentesis but five weeks earlier, a sample of tissue is taken from the developing placental tissue. Both chromosomal and genetic analysis can be performed on this tissue, and the results are available quicker and at an earlier stage of the pregnancy than with amniocentesis. However, there is a higher miscarriage rate following chorionic villus sampling than amniocentesis (Boss, 1994).

Fetal Blood Sampling. Occasionally, when there is concern that a pregnant woman has been exposed to an infection early in her pregnancy, a sample of blood will be taken from the umbilical cord with a very fine needle under ultrasound guidance. This sample is used to assess if the fetus has become infected and at high risk of development problems following the maternal exposure.

New Advances

Advances in prenatal diagnosis have followed rapidly from technological improvements in ultrasound equipment, refinement and experience of current techniques, and the development of new tests. The aim of research in this area is to provide the earliest possible accurate information about the health of the developing baby, and to do so in the way safest for the expectant mothers and their babies. If the information is reassuring, the couple can enjoy the remainder of the pregnancy in the knowledge that everything will progress normally. However, if the result are unfavourable and an abnormality is diagnosed, earlier decisions about potential treatment or termination are possible and so may be less traumatic for those involved.

Fluorescent in situ Hybridisation (FISH). FISH is a technique which uses a specific DNA sequence as a probe to recognise its complementary sequence on a chromosome. The probe has a fluorescent tag attached which lights up when it is attached to the recognised chromosome segment. Recently FISH has been applied to analysis of amniocentesis samples to assess if an extra chromosome 21 is present or not in the cells. Because the amniocentesis cells do not require culturing for this technique the test results can potentially be available sooner than following standard amniocentesis.

Fetal Blood Cells in the Maternal Circulation. At about 6 weeks fetal blood cells can be found in a blood sample taken from a pregnant woman. These cells exists in very small numbers. Recent work has extracted and purified these cells to allow assessment of the fetal chromosome pattern and to determine if the fetus has a specific genetic mutation. Although this technique is very new it has the potential to make the currently used invasive techniques obsolete and will allow very early diagnosis.

Preimplantation Diagnosis. This procedure involves the use of technology developed with in vitro fertilisation (IVF). An oocyte is removed from the woman and brought into contact with spermatozoa from her partner under controlled conditions. One of the spermatozoa effects fertilisation to form a zygote. Following three stages of cell division (this eight-cell stage is termed, the blastocyst), one cell can be removed and used for analysis (Aksoy, 1997a). The DNA sequence of this cell can be determined to identify the presence or absence of a gene mutation that has caused illness in one of the parents. If the cell does not contain the mutation, the blastocyst can be implanted in the womans uterus (womb) to develop into a fetus which is unaffected by the condition that has affected other family members.

Human Genome Project. The aim of the Human Genome Project is to have identified the entire human DNA sequence (genome) by 2005. The extra information generated about specific genes and their association with specific disorders has the potential to expand dramatically the number of genetic tests available to couples with a family history of a genetic condition.

Ethical Issues

It is important to understand the purpose of prenatal diagnosis. It is done to provide parents with information about the health and development of their baby, not to provide them with a reason to have a termination of pregnancy. There are 180,000 terminations performed each year in the United Kingdom, of these 5000 are because of fetal abnormalities diagnosed by prenatal tests. Abortion is a serious problem itself in all regions of the world, developed and developing, and we discussed it in an earlier issue of this magazine (Aksoy 1997b). When prenatal tests reveal that a baby has health problems, parents face a number of difficult questions. Is any treatment available? What are the baby’s chances of survival? What would be the baby’s quality of life if he or she did survive? Some illnesses can be treated during pregnancy and after delivery. One of the main aims of fetal medicine is to develop therapies to treat fetuses and improve the survival. However, some conditions are fatal despite all treatment. In these circumstances couples sometimes take the extremely difficult decision to have a termination of pregnancy

For religious, moral or other reasons many couples opt not to have any tests performed during pregnancy. They feel that even if the results of any test indicated that their baby was affected by a serious condition they should and would continue with the pregnancy. It is important in each situation that the parents’ decisions are respected and supported. The parents need to be given appropriate guidance and counselling rather than be met with disapproval.

In some countries prenatal testing has been extensively used to determine the sex of the baby at an early stage, with the intention of ensuring that only male babies are born (Kusum, 1993). In the United Kingdom, as in many other places, prenatal diagnosis to determine fetal sex is deemed morally unacceptable. It is important that new advances in medicine are paralleled by an informed ethical debate. Prenatal tests should reflect what is appropriate within a society rather than just allowing what is technically feasible. A number of regulatory groups have been formed, including the Human Fertilisation and Embryology Authority (HFEA), to monitor and regulate new advances in this area.

In sum: prenatal diagnosis is a rapidly expanding area of medicine. New techniques are constantly being developed which are aimed at allowing earlier diagnosis, less invasive methods and, ultimately, treatment. It is important that developments are monitored and regulated to ensure that the techniques available are applied within an ethical framework.

REFERENCES

Aksoy, S. (1996) ‘Prenatal Testing: An Ethical Perspective’, The New Journal of Medicine, 13:2, pp.12-14.

Aksoy, S. (1997) ‘Moral Controversies on Preimplantation Genetic Testing’, paper presented at UNESCO Asian Bioetlncs Conference, Kobc-Japan, November 1997.

Aksoy, S. (1997), ‘Abortion: Mercy or Murder?’, The Fountain, 2:17 pp.32-5.

Atkins, A.F.J. and Hey, EN. (1991) ‘The Northern Regional Fetal Abnormality Survey’, in Drife, jO. and Donnai, D.(cds) Antenatal Diagnosis of Fetal Abnormalities, Springer-Verlag Ltd., London.

Boss, J.A. (1994) ‘First Trimester Prenatal Diagnosis: Earlier is not Necessarily Better’, JME, 20 pp.l46-5l. )

Cohen, L.G. (1990 Before Theýr Týme at Risk, American Association on Mental Retardation, Washington DC.

Kusum (1993) ‘The Use of Pre-natal Diagnostic Techniques for Sex Selection: The Indian Scene’, Bioethics, 7: 2/3 pp,149-65.

Moore, K.L. (1989) Before We Are Born: Basic Embryology and Birth Defects, WB. Saunders Comp., Philadelphia.

Sutton, A. (1990) Prenatal Diagnosis: Confronting the Ethical Issues, The Linacre Centre, London.

Wald, NJ. and Cuckle, H.S. (1992) ‘Biochemical Screening’, in Brock, D.J.H., Rodeck, C.H. and Ferguson-Smith, MA.(eds) Prenatal Diagnosis and Screening, Churchill Livingstone, Edinburgh.