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Statistics
Statistics deals with collecting, organizing, and interpreting numerical data. An important aspect of statistics is the analysis of population characteristics inferred from sampling.
36,756 Questions
What age groups does bulimia mostly affect?
Bulimia most commonly affects adolescents and young adults, typically between the ages of 18 to 30. However, it can also occur in individuals of any age, including older adults and teenagers.
What is Importance of pilot survey during a large survey?
1. Alert the surveyor to any difficulties that were not anticipated to the survey method stage. 2. Ensure that proposed methods and procedures Will work properly in practice before being applied to the large, expensive investigation. 3. It provide an opportunity to the surveyor to prepare for adjustments and revisions before investing in. 4. Gather information prior to a larger study to improve the later's quality and efficiency. 5. Reveals deficiencies in the design of the procedures and experiments that were to be applied to the main study. 6. The importance of pilot survey becomes more clear when it is able to detect a flaw in the proposed method and gives an awareness for a more careful planning.
Is it possible to predict winning lottery numbers in advance?
No, not unless you have physic powers which I'm assuming you don't.
Lottery numbers are random and could not be predicted without "powers" good luck though.
What groups are most affected by stereotypes?
Groups that are most affected by stereotypes include racial and ethnic minorities, the LGBTQ+ community, individuals with disabilities, and religious minorities. Stereotypes can lead to discrimination, prejudice, and social exclusion, negatively impacting these groups' opportunities and experiences.
What is A shift from high birthrates and death rates to low birthrates and death rates?
This transition is known as the demographic transition, which typically occurs as a society advances economically and socially. Factors such as improved healthcare, education, and access to family planning contribute to declining birth and death rates. This shift leads to changes in population structure and can impact a country's social and economic development.
What age bracket herpes dose it affect the most?
Herpes can affect individuals of any age, but it is most commonly seen in young adults between the ages of 20-29 due to factors such as sexual activity. However, herpes can also affect older adults and even children who may be exposed to the virus through non-sexual means.
Individuals in their twenties represent about 18 percent of the adult US population but account for around 30-35 percent of total convictions in the US.
What are the roles of theories in research?
1- it orgnized the society.2-It provides equal chances to all eligible people.3-It makes balanced measurement for available social values.4-Social evils are being eradicated by it. 5.public programs are being framed by adminstrators.6- jurists take proper decesions.
What was the population growth rate in the US from 1990 to 2000?
The population growth rate in the US from 1990 to 2000 was approximately 13.2%. During this decade, the population increased from around 248.7 million to 281.4 million people.
Survey sampling is better than census survey?
Only in terms of cost, time to complete, resources-those kinds of measures. A census provides complete information if done properly which is not possible with just a sample. A sample is always subject to sampling error.
What ih Infant mortality rate in Maharashtra's?
The infant mortality rate in Maharashtra is approximately 19 per 1,000 live births. This rate is an important indicator of the overall health and well-being of a population, and efforts are continuously being made to reduce it through better healthcare services and interventions.
What are the sources of errors in compass survey?
Dead Reckoning and Compass SensorsDead reckoning is the mathematical process of calculating the current position of an object based on knowledge of the location of its previous position and the distance and direction it travelled from this position to reach its current position. It is a navigational system which has been in use since medeval times and is very popular in robotics. Whilst deadreckoning is one of the simplest forms of navigation, implementation of the method suffers from an unbounded accumulation of errors. These errors can be significantly reduced if an absolute direction reference is available for the dead reckoning calculations.
Geomagnetic compass sensors provide an absolute direction reference. Provided there are no local sources of ferrous material or magnetic fields a freely suspended magnet will always point to the magnetic north pole. The Earth generates a magnetic field due to the motion of liquid layers which surrounds the Earth's iron core. The field surrounds the Earth and the north magnetic pole is located in the Parry Islands of northern Canada approximately 400 km from the axial north pole.
Large errors can be induced in geomagnetic compasses by the close proximity of a magnetic field or source of ferrous material. This is often stated as the main reason for not using these sensors. What follows is a description of a system which has been designed to identify and where possible remove this source of error. Geomagnetic Compass ErrorsThe magnetic field surrounding the Earth and the north magnetic pole is located approximately 400 km from the axial north pole but constantly moves. The resulting field is horizontal at the equator and vertical at the magnetic poles. In the absence of any local sources of ferrous material or magnetic fields a geomagnetic compass will always point to the magnetic north pole. Additional errors can also be induced in a geomagnetic compass by the vertical portion of the earth's magnetic field, these errors are greatest near the magnetic poles. The geographic location of the UK results in these errors being insignificant provided the compass sensors are kept horizontal.
The position of the magnetic pole with respect to the axial pole and the movement of the magnetic field produce a declination which varies with time and geographic location. The amount and variation with time of the declination for any given area is printed on Ordinance Survey maps and can easily be incorporated into dead reckoning software. The declination correction need only be applied if the heading information is to be related to true north rather than magnetic north.
Of greatest significance are the errors induced by the close proximity of ferrous objects or local magnetic fields such as those produced by electric cables or the magnets in motors. It is often stated that it is difficult to use geomagnetic compass sensors indoors due to the distortion from electric cables and steel structures and this is the main reason for not using a compass. Any deviations to the geomagnetic compass sensors due to the vehicle on which it is mounted can be reduced by the placement of compensating magnets or iron bars in the close proximity of the compass. This technique is described in detail in the old Admiralty Handbooks published by HMSO.
Ferrous objects, in particular large objects such as ships, gain a permanent magnetic field during construction due to the electric currents used during welding and the effects of hammering and heating the metal during riveting or forming the members. If the object is left in one position for a long period of time it will also gain an induced magnetic field due to the effects of the earth's magnetic field.
The deviation of any geomagnetic compass mounted on the vehicle will vary with the direction the vehicle is pointed and with latitude. The deviation may be reduced by placing small corrector magnets, soft iron spheres and soft iron bars known as flinder's bars around the perimeter of the compass. The process is one of trial and error which used to be carried out yearly on naval vessels. The Aldmiralty Handbook also required that the officer of the watch remove his keys, knife and any other magnetic objects from his person before using the ship's compass.
Whilst the full process of correcting a compass may be excessive for the application of compasses in robotics it does highlight the need to site the sensor carefully to avoid deviations and to choice the materials out of which the robot is constructed carefully. When mounting the compass sensors on the wheelchair chassis which was to be used as a mobile robotics platform it was found that the effect of the steel frame and motor magnets diminished significantly if the sensor was kept at least 150 mm from any such objects. As a result the sensors were mounted on a copper tubing frame at the front of the wheelchair.
Background reading failed to find any methods to directly reduce or eliminate the effect of errors sources other than those associated with the vehicle on which the sensors were mounted. Although several sources suggested that the fusion of the compass sensor data with data from other sensors may overcome the problem. External Error Source IdentificationThe possible sources of error due to external phenomena or objects identified during background research were magnetic fields associated with electric cables and the attraction of the geomagnetic compass sensor to ferrous metal objects such as heating radiators or structural steel members. Trials with a hand held compass designed for mountaineers suggested that such objects influenced the compass at a distance of approximately 300 mm.
A basic principle of physics was exploited to provide an innovative means of identifying and correcting for external error sources. Due to the distance travelled the light from the sun is assumed to be from a point source and all the light rays are assumed to be parallel to each other. Any source which is an infinite distance from a detector will produce radiation in parallel rays. If the magnetic north pole, towards which all geomagnetic compasses point, is assumed to be an infinite distance from the geomagnetic compass then this principle will also apply. Thus all geomagnetic compasses will point in the same direction regardless of the separation between the individual compasses. Whilst strictly this is not true, the declination variation (taken from an Ordinance Survey map) is 3.24" per meter in the area the project work was carried out. This figure is 2 orders of magnitude less than the typical manufacturer's stated accuracy of compass sensors and significantly less than the 10' annual change in declination.
To implement this principle a number of geomagnetic compass sensors need to be arranged such that it is not possible for an external ferrous source or magnetic field to effect all of the compass sensors in the same manner. If enough sensors are used it is then possible to use a voting system to choice the correct bearing to magnetic north if all of the sensors are not giving the same reading. With only two sensors it is possible for an external ferrous material source or magnetic field directly in line with the two sensors to produce a result similar to that of the magnetic north pole. By using a triangular formation it is not possible for an external magnetic field or source of ferrous material to produce the same deviation in all three compasses, but it is possible for two of the sensors to be indicating the same direction incorrectly and thus causing an error in the voting system. A minimum of five sensors arranged in a pentagon are required to ensure that a voting system will always indicate a true bearing to magnetic north, although this arrangement would still fail in the presence of a very large external magnetic field. The Resource constraints will usually limit the system to the use of three compass sensors arranged to occupy the points of a triangle. The length of the sides of the triangle are limited by the wheelchair frame footprint and are approximately 300 mm long. Figures below show the operation of the compasses under a variety of situations.
Figure 1
Figure 2
Figure 3
Figure 1 shows the direction indicated by the compass sensors when the robot is travelling towards magnetic north with all of the sensors pointing in the same direction. If the robot undertakes a 90o turn the three compass are all still pointing in the same direction as shown in figure 2. However if, as shown in figure 3, the compass sensors are influenced by an external ferrous material or magnetic field source at least one and possibly all three sensors will point to the error source. In order to produce an error the error source must be close to the robot in which case the distance from the source to the sensor can no longer be assumed to be infinite. As a result the sensors will not all give indicate the same direction and this can be detected by the compass sensor processing software, action can now be taken on discovering the discrepancy.
What are significant variables?
Significant variables are the variables whose change will alter or affect the outcome of the experiment. Variables that are not significant may also alter the outcome, but this change is a statistical error, not a systematic change. For example if you are trying to estimate how much food will be consumed in an event, a variable is how many people will attend the event and another is how tall are the people that attend it. The first variable is significant, whereas the latter isn't.
What kind of study would a survey be?
A survey would typically be considered a form of descriptive research. This type of study is used to gather information about people's thoughts, opinions, behaviors, or characteristics through a structured questionnaire or interview. It aims to describe the current state of a population or phenomenon.
Is data centralized in organizations?
Often. Centralized data today is usually considered centralized electronic databases instead of filing cabinets with records.
The opposite to centralized data, is compartmentalized. Business organization take advantage of centralized data bases to perform statistical analysis accross divisions. I will give you an example. One division of a computer company might sell printers, and another hard drives. By having a central database, all purchases by the same customers can be compared.
Compartmentalized data storage is done usually for security reasons. Two examples are patient records in hospitals and military security. Separate computer installations and established protocols for what information can be accessed by whom are necessary.
In the media it has been reported that credit card databases have been entered and many records copied. It is one area where there are pros and cons of centralized data bases, which serves both marketing needs and verifies transactions. There are also pros and cons of centralized police records, which may contain incorrect information, and are easily accessible.
What are the objective and subjective determinants of consumption?
Objective determinants of consumption include factors such as income, prices, and interest rates that impact how much individuals can afford to spend. Subjective determinants of consumption involve personal preferences, tastes, and attitudes towards saving and spending that influence consumer behavior. Both types of determinants interact to shape overall consumption levels in an economy.
How can birth rates and death rates affect a ecosystem?
It affects the ecosystem because if there is a dramatic increase in birthrates, it may over populate the world. If there is an increase in death rates, there will be a dramatic change in population. It's very hard to explain.
What age group is affected most by divorce?
Children and adolescents are most affected by divorce, as they may face emotional and psychological challenges during this time. Research suggests that younger children may struggle with feelings of abandonment, while adolescents may experience increased levels of stress and conflict. Support and guidance from caring adults are crucial to help children navigate these difficulties.
A credentialistic meritocracy is dependent upon the utilization of ascriptive variables?
In a credentialistic meritocracy, individuals are judged and rewarded based on their academic and professional credentials rather than other factors like race or social status. Ascriptive variables such as race, gender, or social background should not be the determining factors in assessing someone's merit in this system. This ensures a more fair and equal opportunity for all individuals to succeed based on their qualifications and achievements.
What percentage of the world are creationists?
I don't think that you could accurately determine the percentage. There are those that believe in creation and those that believe in evolution. A large part of those that say they believe in creation also believe in evolution to some degree. If you are taking a count of who believes what, put me down for creation with no evolution.
The three criteria for causality are temporal precedence, covariation of cause and effect, and elimination of alternative explanations. Temporal precedence establishes that the cause must precede the effect in time, covariation shows that changes in the cause are consistently followed by changes in the effect, and alternative explanations must be eliminated to establish a causal relationship. All three criteria are needed to ensure that the observed relationship between variables is indeed causal and not due to other factors.
What is the difference between the principle of Tacheometric survey and Totalstation survey?
The main difference is the method of measuring distances. Tacheometry is optical. A total station uses electromagnetic waves.
Distances measured using Tacheometry are determined by multiplying the difference in readings to a levelling staff between the upper and lower stadia hairs, by a constant (usually 100).
A Total station, by definition, is a theodolite with a built-in EDM measuring device. This sends out a signal of a known wavelength to a reflector and calculates the distance by measuring the time it takes for the signal to return.
Does Population density refers to the number of individuals found within a given area true or false?
That's one definition so I'll go for true. The other definition is the number of defined units per a defined space. The defined space can be one dimensional (along a river), two dimensional (area) and three dimensional (number of fish per cubic meter of water). Or, the number of defined units per a defined space at some point in time. See related link.
Population of Americans between the ages of 18-65?
As of 2020, the estimated population of Americans between the ages of 18-65 is around 213 million. This age range represents the working-age population in the United States.
What is significant difference?
A significant difference refers to a statistically meaningful distinction between two or more groups or variables. It implies that the difference observed is unlikely to have occurred by chance and is likely to have practical relevance. Statistical tests are used to determine if a difference is significant.
