Simple Random Sampling vs. Systematic Random Sampling

Simple Random Sampling vs. Systematic Random Sampling When we form a statistical sample we always need to be careful in what we are doing. There are many different kinds of sampling techniques that can be used.  Some of these are more appropriate than others. Often what we think would be one kind of sample turns out to be another type. This can be seen when comparing two types of random samples. A simple random sample and a systematic random sample are two different types of sampling techniques. However, the difference between these types of samples is subtle and easy to overlook.  We will compare systematic random samples with simple random samples. Systematic Random vs. Simple Random To begin with, we will look at the definitions of the two types of samples that we are interested in.  Both of these types of samples are random and suppose that everyone in the population is equally likely to be a member of the sample. But, as we will see, not all random samples are the same. The difference between these types of samples has to do with the other part of the definition of a simple random sample. To be a simple random sample of size n, every group of size n must be equally likely of being formed. A systematic random sample relies on some sort of ordering to choose sample members. While the first individual may be chosen by a random method, subsequent members are chosen by means of a predetermined process. The system that we use is not considered to be random, and so some samples that would be formed as a simple random sample cannot be formed as a systematic random sample. An Example Using a Movie Theater To see why this is not the case, we will look at an example. We will pretend that there is a movie theater with 1000 seats, all of which are filled. There are 500 rows with 20 seats in each row. The population here is the entire group of 1000 people at the movie. We will compare a simple random sample of ten moviegoers with a systematic random sample of the same size. A simple random sample can be formed by using a table of random digits. After numbering the seats 000, 001, 002, through 999, we randomly choose a portion of a table of random digits. The first ten distinct three digit blocks that we read in the table are the seats of the people who will form our sample.For a systematic random sample, we can begin by choosing a seat in the theater at random (perhaps this is done by generating a single random number from 000 to 999). Following this random selection, we choose this seat’s occupant as the first member of our sample. The remaining members of the sample are from the seats that are in the nine rows directly behind the first seat (if we run out of rows since our initial seat was in the back of the theater, we start over in the front of the theater and choose seats that line up with our initial seat). For both types of samples, everyone in the theater is equally likely to be chosen. Although we obtain a set of 10 randomly chosen people in both cases, the sampling methods are different. For a simple random sample, it is possible to have a sample that contains two people who are sitting next to each other. However, by the way that we have constructed our systematic random sample, it is impossible not only to have seat neighbors in the same sample but even to have a sample containing two people from the same row. What’s the Difference? The difference between simple random samples and systematic random samples may seem to be slight, but we need to be careful. In order to correctly use many results in statistics, we need to suppose that the processes used to obtain our data were random and independent. When we use a systematic sample, even if randomness is utilized, we no longer have independence.

Modern Female Infanticide in Asia

Modern Female Infanticide in Asia In China and India alone, an estimated 2,000,000 baby girls go missing each year. They are selectively aborted, killed as newborns, or abandoned and left to die. Neighboring countries with similar cultural traditions, such as South Korea and Nepal, have also faced this problem.   What are the traditions that lead to this massacre of baby girls? What modern laws and policies have addressed or exacerbated the problem? The root causes of female infanticide are similar but not exactly the same in Confucian countries like China and South Korea, versus predominantly Hindu countries such as India and Nepal. India and Nepal According to Hindu tradition, women are lower incarnations than men of the same caste. A woman cannot obtain release (moksha) from the cycle of death and rebirth. On a more practical day-to-day level, women traditionally could not inherit property or carry on the family name. Sons were expected to take care of their elderly parents in return for inheriting the family farm or shop. Daughters drained the family of resources  because they had to have an expensive dowry to get married; a son, of course, would bring dowry wealth into the family. A womans social status was so dependent on that of her husband that if he died and left her a widow, she was often expected to commit sati rather than going back to her birth family. As a result of these beliefs, parents had a strong preference for sons. A baby girl was seen as a robber, who would cost the family money to raise, and who then would take her dowry and go to a new family when she got married. For centuries, sons were given more food in times of scarcity, better medical care, and more parental attention and affection. If a family felt like they had too many daughters already, and another girl was born, they might smother her with a damp cloth, strangle her, or leave her outside to die. In recent years, advances in medical technology have made the problem much worse. Instead of waiting nine months to see which gender the baby would be, families today have access to ultrasounds that can tell them the childs gender just four months into the pregnancy. Many families who want a son will abort a female fetus. Sex determination tests are illegal in India, but doctors routinely accept bribes to carry out the procedure, and such cases are almost never prosecuted. The results of gender-selective abortion have been stark. The normal sex ratio at birth is about 105 males for each 100 females  because girls naturally survive to adulthood more often than boys. Today, for each 105 boys born in India, only 97 girls are born. In the most skewed district of Punjab, the ratio is 105 boys to 79 girls. Although these numbers dont look too alarming, in a country as populous as India, that translates to 37 million more men than women as of 2014. This imbalance has contributed to a rapid rise in horrific crimes against women. It seems logical that where women are a rare commodity, they would be treasured and treated with great respect. However, what happens in practice is that men commit more acts of violence against women where the gender balance is skewed. In recent years, women in India have faced increasing threats of rape, gang rape, and murder, in addition to domestic abuse from their husbands or their parents-in-law. Some women are killed for failing to produce sons, perpetuating the cycle. Sadly, this problem seems to be growing more common in Nepal, as well. Many women there cannot afford an ultrasound to determine the sex of their fetuses, so they kill or abandon baby girls after they are born. The reasons for the recent increase in female infanticide in Nepal are not clear. China and South Korea In China and South Korea, peoples behavior and attitudes today are still shaped to a large degree by the teachings of Confucius, an ancient Chinese sage. Among his teachings were the ideas that men are superior to women, and that sons have a duty to take care of their parents when the parents grow too old to work.   Girls, in contrast, were seen as a burden to raise, just as they were in India. They could not carry on the family name or blood-line, inherit the family property, or perform as much manual labor on the family farm. When a girl married, she was lost to a new family, and in centuries past, her birth parents might never see her again if she moved to a different village to marry. Unlike India, however, Chinese women do not have to provide a dowry when they marry. This makes the financial cost of raising a girl less onerous. However, the Chinese governments One Child Policy, enacted in 1979, has led to gender imbalance similar to Indias. Faced with the prospect of only having a single child, most parents in China preferred to have a son. As a result, they would abort, kill, or abandon baby girls. To help alleviate the problem, the Chinese government altered the policy to allow parents to have a second child if the first one was a girl, but many parents still do not want to bear the expense of raising and educating two children, so they will get rid of girl babies until they get a boy. In parts of China today, there are 140 men for every 100 women. The lack of brides for all of those extra men means that they cannot have children and carry on their families names, leaving them as barren branches. Some families resort to kidnapping girls in order to marry them to their sons. Others import brides from Vietnam, Cambodia, and other Asian nations. In South Korea, too, the current number of marriage-age men is much larger than the available women. This is because, in the 1990s, South Korea had the worst gender-at-birth imbalance in the world. Parents still clung to their traditional beliefs about the ideal family, even as the economy grew explosively and people grew wealthy. In addition, educating children about the sky-high standards common in Korea is very expensive. As a result of growing wealth, most families had access to ultrasounds and abortions, and the nation as a whole saw 120 boys being born for every 100 girls throughout the 1990s. As in China, some South Korean men today are bringing brides in from other Asian countries. However, it is a difficult adjustment for these women, who usually dont speak Korean and dont understand the expectations that will be placed on them in a Korean family - particularly the enormous expectations around their childrens education. Yet South Korea is a success story. In just a couple of decades, the gender-at-birth ratio has normalized at about 105 boys per 100 girls. This is mostly a result of changing social norms. Couples in South Korea have realized that women today have more opportunities to earn money and gain prominence - the current prime minister is a woman, for example. As capitalism booms, some sons have abandoned the custom of living with and caring for their elderly parents, who are now more likely to turn to their daughters for old-age care. Daughters are growing ever more valuable. There are still families in South Korea with, for example, a 19-year-old daughter and a 7-year-old son. The implication of these bookend families is that several other daughters were aborted in between. But the South Korean experience shows that improvements in the social status and earning potential of women can have a profoundly positive effect on the birth ratio. It can actually prevent female infanticide.