# An engineer has performed an experiment to study the effect of four

In statisticsa full factorial experiment is an experiment whose design consists of two or more factors, each with discrete possible values or "levels", and whose experimental units take on all possible combinations of these levels across all such factors. A full factorial design may also be called a fully crossed design.

Such an experiment allows the investigator to study the effect of each factor on the response variableas well as the effects of interactions between factors on the response variable. For the vast majority of factorial experiments, each factor has only two levels.

If the number of combinations in a full factorial design is too high to be logistically feasible, a fractional factorial design may be done, in which some of the possible combinations usually at least half are omitted. Ronald Fisher argued in that "complex" designs such as factorial designs were more efficient than studying one factor at a time.

The writer is convinced that this view is wholly mistaken. Nature, he suggests, will best respond to "a logical and carefully thought out questionnaire". A factorial design allows the effect of several factors and even interactions between them to be determined with the same number of trials as are necessary to determine any one of the effects by itself with the same degree of accuracy. Frank Yates made significant contributions, particularly in the analysis of designs, by the Yates analysis.

The term "factorial" may not have been used in print beforewhen Fisher used it in his book The Design of Experiments. Many people examine the effect of only a single factor or variable.

Compared to such one-factor-at-a-time OFAT experiments, factorial experiments offer several advantages [4] [5].

### Study Alone vs. Group Study

In his book, Improving Almost Anything: Ideas and Essaysstatistician George Box gives many examples of the benefits of factorial experiments. Here is one. The engineers asked Christer Hellstrand, a statistician, for help in designing the experiment.

Box reports the following. Christer asked if there were other factors they would like to test. They said there were, but that making added runs would exceed their budget. Christer showed them how they could test two additional factors "for free" â€” without increasing the number of runs and without reducing the accuracy of their estimate of the cage effect.

The various combinations can conveniently be shown as the vertices of a cube The factors changed were heat treatment, outer ring osculation, and cage design. The numbers show the relative lengths of lives of the bearings. If you look at [the cube plot], you can see that the choice of cage design did not make a lot of difference. A likely explanation is that, because most engineers have, until recently, employed only one factor at a time experimentation, interaction effects have been missed.

The simplest factorial experiment contains two levels for each of two factors. Suppose an engineer wishes to study the total power used by each of two different motors, A and B, running at each of two different speeds, or RPM.

Each combination of a single level selected from every factor is present once.Psychedelic agents in creative problem-solving experiment was a study designed to evaluate whether the use of a psychedelic substance with supportive setting can lead to improvement of performance in solving professional problems.

The altered performance was measured by subjective reports, questionnaires, the obtained solutions for the professional problems and psychometric data using the Purdue Creativity, the Miller Object Visualization, and the Witkins Embedded Figures tests. Some weeks before the actual experiment, a preliminary experiment was conducted. It consisted of two sessions with four participants in each. The groups worked on two problems chosen by the research personnel. The first group consisted of four people with professional experience in electrical engineering, engineering design, engineering management and psychology.

They were given 50 micrograms of LSD. The second group consisted of four research engineers, three with a background in electronics and one in mechanics. They were given milligrams of mescaline. Both groups were productive in ideation but, according to Fadiman, the fact that the participants didn't have actual personal stake in the outcome of the session negatively affected the actualization of the ideas.

This is why the actual study focused on personal professional problems that the participants were highly motivated to tackle. McKimRobert E.

## Experimental Effect

MogarJames Fadiman and Myron Stolaroff. The participants of the study consisted of 27 male subjects engaged in a variety of professions: sixteen engineers, one engineer-physicist, two mathematicians, two architects, one psychologist, one furniture designer, one commercial artist, one sales manager, and one personnel manager.

Nineteen of the subjects had had no previous experience with psychedelics. Each participant was required to bring a professional problem they had been working on for at least 3 months, and to have a desire to solve it. Commonly observed characteristics of the psychedelic experience seemed to operate both for and against the hypothesis that the drug session could be used for performance enhancement.

The research was therefore planned so as to attempt to provide a setting that would maximize improved functioning, while minimizing effects that might hinder effective functioning. They received instructions and introduced themselves and their unsolved problems to the group. Approximately one hour of pencil-and-paper tests were also administered. At the beginning of the day of the experiment session, subjects were given milligrams of mescaline sulphate a moderately light dose compared to the doses used in experiments to induce mystical experiences.

After some hours of relaxation, subjects were given tests similar to the ones on the introduction day.Rob Stein. The genetic variation Chinese scientist He Jiankui was trying to re-create when he edited twin girls' DNA may be more harmful than helpful to health overall, a new study says. It appears that the genetic variation a Chinese scientist was trying to re-create when he edited twin girls' DNA may be more harmful than helpful to health overall, according to a study published Monday.

But there's also evidence the CCR5 variation has other effects, such as making people more vulnerable to the West Nile and influenza viruses. The question is: Is it overall beneficial or detrimental to have this mutation? So Nielsen and his colleagues analyzed more thanpeople whose genes and health records are stored in the UK Biobank in Britain.

We were quite surprised the effect was this large. The reason isn't entirely clear, but Nielsen thinks it's probably because of an increased vulnerability to the flu. The findings underscore why it was premature for the Chinese scientist to do what he did, Nielsen says. And one of them is fact that we can't really predict the effect of the mutations that we induce," Nielsen says.

Daley notes that according to data the Chinese scientist presented last year, He apparently didn't even manage to edit the gene as intended. So it remains far from clear how the modification he did achieve will affect the girls. So the experiment done in China was a failure â€” not just ethically, but scientifically," Daley says. The first monoclonal antibodies were nearly deadly. The first gene therapies were indeed deadly. All kinds of means of transportation were and still are deadly.

It's all about benefits versus risks," Church says. But many scientists, bioethicists and advocates worry other scientists will misuse the technology prematurely. Soon after He's announcement, the Chinese scientist says he was contacted by at least one infertility clinic in Dubai congratulating him and asking if he would teach them how to do what he did, according to William Hurlbuta scientist and bioethicist at Stanford who has been in touch with He.

Any changes made in human embryos could be passed down for generations, which is why this sort of genetic manipulation has long been considered off-limits. It's not like you're just dealing with an individual patient. You're now dealing with the entire human gene pool.

But Hurlbut, while stressing that he repeatedly tried to persuade He against doing what he did, says that He had good intentions. Hurlbut says He was genuinely trying to help prevent the spread of HIV in China, where the disease remains very common in some places and highly stigmatized. Accessibility links Skip to main content Keyboard shortcuts for audio player. NPR Shop.As we all enter into college, or have been here for a couple semesters, studying still stands as something that can constantly be improved upon.

Heading into every single quiz, exam, or project it is always impertinent that you study before hand to be as prepared as possible. However, what is the best way to study? Do I go sit in the deep gallows of the stacks, completely isolated, or do I gather with a few of my friends who are also studying? Studying alone can also have many different parameters, from being completely isolated from all civilization in the stacks, to simply being a table by yourself with your headphones in.

This strategy absolutely comes with different advantages and disadvantages. Advantages to studying alone are that it minimizes distraction, allows you to pace yourself, and can improve your focus. When you are by yourself, distraction is minimized due to the lack of other interaction you have other than with your schoolwork.

You can take breaks whenever you feel overwhelmed, or even read at a speed that suits you. This pacing of your own work can be extremely beneficial to you, for no one knows you better than yourself. Lastly, the improvement of focus that comes with studying alone is crucial.

This lets you have the flexibility to learn different sections that you personally need improvement on as well as leave less stress on aspects you may have already mastered Getcollegecredit. Disadvantages to studying alone is not having your peers and friends around you to push you to study if you become off task.

Even the best of studiers can sometimes become off task for hours without even realizing it. Having that group around you will allow you to push to maximize the time you spend studying blog. When you study in a group of people, like studying alone, will come with advantages and disadvantages.

Group studying typically involves anywhere from one to four other people that will studying either the same, or different, material that you are. Some advantages to this study technique are it can increase retention, expand access to information, and boost motivation to study. This increased retention will come from the ability to vocalize ideas you may have to someone else, a technique that is proven to allow you to remember information better. Along with this will come the knowledge not just that you have, but the knowledge from everyone else around the table.

The biggest advantage will come from the increased motivation that comes from a group study. Having others around you that are also studying, will prevent distraction and allow you to maximize this study effort Getcollegecredit. This means that if there is one person that is extremely distracted, too loud, or constantly being outlandish it can be detrimental to the group as a whole.

If that one person is off, every single member of the group can suffer for his or her actions classroom. I think that one way in which this could be decided is through a study. This study could gather random people that are separated into random group. Then each group will either study individually or within a group, and given an exam to see who scores better.

This is just an idea that could be purposed in order to determine which study method yields better school performance. Every single person studies and performs in different ways, whether that be with a group of friends or independently. Studying is no different. In order to succeed you must try each option and stick to what works. Personally, I enjoy studying with groups because I feel less stress and feel like they keep me on task more often.

When I am studying alone I can sometimes catch myself an hour into random videos on YouTube. Each method has several different advantages and disadvantages, it is up to you to decide which method will yield the best results.

I find that when I am studying for a test, I prefer to study on my own.The energy quantization of electromagnetic radiation in general, and of light in particular, is expressed in the famous relation. The notion of light quantization was first introduced by Planck.

Its validity is based on solid experimental evidence, most notably the photoelectric effect. The basic physical process underlying this effect is the emission of electrons in metals exposed to light.

No photoelectrons are emitted from the metal when the incident light is below a minimum frequency, regardless of its intensity. The value of the minimum frequency is unique to each metal.

Photoelectrons are emitted from the metal when the incident light is above a threshold frequency. The kinetic energy of the emitted photoelectrons increases with the frequency of the light.

The number of emitted photoelectrons increases with the intensity of the incident light. However, the kinetic energy of these electrons is independent of the light intensity. Consider the conduction electrons in a metal to be bound in a well-defined potential. In the classical model, a photoelectron could be released if the incident light had sufficient intensity. However, Eq. When the incident light intensity is increased, more photons are available for the release of electrons, and the magnitude of the photoelectric current increases.

From Eq. The photoelectric current in a typical setup is extremely small, and making a precise measurement is difficult. Normally the electrons will reach the anode of the photodiode, and their number can be measured from the minute anode current. However, we can apply a reverse voltage to the anode; this reverse voltage repels the electrons and prevents them from reaching the anode.

In this experiment, we will measure the stopping potential with modern electronics. The central element of the apparatus is the photodiode tube. The diode has a window which allows light to enter, and the cathode is a clean metal surface. To prevent the collision of electrons with air molecules, the diode tube is evacuated.

To measure the stopping potential, we use a very sensitive amplifier which has an input impedance larger than 10 13 ohms. The amplifier enables us to investigate the minuscule number of photoelectrons that are produced. It would take considerable time to discharge the anode at the completion of a measurement by the usual high-leakage resistance of the circuit components, as the input impedance of the amplifier is very high.

The amplifier output will not stay at 0 volts very long after the switch is released. However, the anode output does stabilize once the photoelectrons charge it up.

There are two 9-volt batteries already installed in the photodiode housing. To check the batteries, you can use a voltmeter to measure the voltage between the output ground terminal and each battery test terminal. The battery test points are located on the side panel.

### Study of the Effects of Alcohol on Drivers and Driving Performance on Straight Road

You should replace the batteries if the voltage is less than 6 volts. This experiment requires the use of several different monochromatic light beams, which can be obtained from the spectral lines that make up the radiation produced by excited mercury atoms.Drinking driving is responsible for a high proportion of traffic accidents. The investigation results revealed that alcohol affected drivers in many aspects, including attitude, judgment, vigilance, perception, reaction, and controlling.

The analysis of accident rate showed that higher BAC level would lead to higher accident rate.

## Experimental Effect

The statistical analysis results of driving performance indicated that average speed, speed standard deviation, and lane position standard deviation were significantly higher under the influence of alcohol. They also had a statistically significant linear trend as the function of BAC level. The discrimination of drinking driving based on driving performance was performed with Fisher discrimination method. The results showed that drinking driving with higher BAC level was easier to discriminate from normal driving.

Also, the results indicated that the three significant indicators on straight roadway could be used in the discrimination of drinking driving state. The conclusions can provide references for the study of drinking driving and the identification of driving state and then contribute to traffic safety. It has been known that alcohol use impairs driving skills and increases accident risk. It has been found that while driving under the influence of alcohol, the risk of having an accident causing injury or death increases exponentially [ 1 ].

In Europe, drinking driving is thought to be responsible for 10, deaths each year [ 2 ]. In China, Li et al. Drunk driving has a high probability to lead to serious accidents.

Even with a small amount of alcohol assumption, drivers are twice likely to be involved in traffic accidents than sober drivers [ 5 ].

Therefore, many countries have been working on solutions to drunk driving for a long period of time, including publicity and education and tough drunk-driving laws.

The laws have been enacted to prohibit driving after drinking and have imposed severe penalties on violators [ 6 ]. The legal limits for BAC are between 0. The limit, for example, is 0. In China, driving with a BAC higher than 0.

Moreover, driving with a BAC higher than 0. Even so, drinking driving is still difficult to be completely eliminated. It was concluded that alcohol consumption, even at low doses, significantly affected driving-related skills such as vision, braking behavior, and vigilance [ 7 ]. Nash demonstrated that drivers would be distracted by alcohol when they were asked to complete some tasks [ 8 ]. Williamson et al. Alcohol not only affects the parameters mentioned above but also causes decline in driving performance.

Linnoila et al. Alcohol also decreases hand steadiness [ 14 ] and operating accuracy at a BAC level of 0.If you look at many industries today you see similar products being offered by multiple manufacturers.

Many companies today are frequently re-designing their products in an attempt to make their product stand out from the crowd. In addition, a great number of manufacturers are constantly developing new products to gain a foothold in other markets.

With new products come new or changed processes. Every time we change a design or process we introduce new content. The amount of new content can be equated to the level of risk in the design or process. Product validation testing and prototype production runs are effective, but costly and in many cases problems are detected late in the development process. Engineers must use various analysis tools and statistical methods to reduce risk in a design or process.

They must evaluate every change and how it could affect the process output. If you have multiple changes occurring at one time you could be multiplying your risk.

So what can be done to predict how a set of changes will likely affect the process output? Design of Experiments DOE is a statistical tool available to engineers that can be used to evaluate single changes or multiple changes to a process at once and predict the resulting change to the output of the process. Design of Experiments DOE is a branch of applied statistics focused on using the scientific method for planning, conducting, analyzing and interpreting data from controlled tests or experiments.

DOE is a mathematical methodology used to effectively plan and conduct scientific studies that change input variables X together to reveal their effect on a given response or the output variable Y.

In plain, non-statistical language, the DOE allows you to evaluate multiple variables or inputs to a process or design, their interactions with each other and their impact on the output. In addition, if performed and analyzed properly you should be able to determine which variables have the most and least impact on the output. By knowing this you can design a product or process that meets or exceeds quality requirements and satisfies customer needs.

DOE allows the experimenter to manipulate multiple inputs to determine their effect on the output of the experiment or process.

By properly utilizing DOE methodology, the number of trial builds or test runs can be greatly reduced. A robust Design of Experiments can save project time and uncover hidden issues in the process.