Z –Test: a statistical test used for inference (inference – is the act or process of deriving logical conclusions from evidence, statements, ideas, etc. known or assumed to be true) which determines if the difference between a sample mean and the population mean is large enough to be statistically significant, that is, if it is unlikely to have occurred by chance. The Z – test is used primarily with its standardized testing to determine if the test scores of a particular sample of test takers are within or outside of the standard performance of test taking. T – Test: gives an indication of the distinctiveness of two sets of measurements, and is then used to check whether two sets of measurements are in essence different and are usually determined through an experimental demonstration. The standard way of doing this is with the null- hypothesis that means (means – a type of average) of the two sets of measures are equal. An example of a Z – test: three people are given some wheat bread to eat and then there blood sugar count is tested a few hours later and the results are that their blood sugar count is hypothetical 100. The next day the same three people are given a Snickers candy bar to eat and then their blood sugar is tested a few hours later and the results is that there blood sugar count is hypothetically 50. The statistical results show that eating wheat products produces a higher blood sugar counts. An example of a T – test: a group of people who have lived in a city and are now considering retirement will most likely move into a gated community where as a group of people who have lived in the country or in a small town are most likely to live in a non-gated community.

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QoS Techniques: MPLS
CET 2486C – Network Technologies
Professor:
November 27, 2012
Abstract
MPLS or Multi Protocol Label Switching is a networking technology that functions between layers 2 and 3 of the OSI model. MPLS constitutes of adding a label (sometimes called “Shim” because of their placement between layer 3 and layer 2 headers.) to the data package, this label contains special addressing and sometimes prioritization information. Because the MPLS label contains all the information necessary for the router to forward the package to the next hop, the router does not have to spend time analyzing the entire package thus improving network latency or bottlenecks. Due to its multi protocol capabilities MPLS can be integrated with different networking technologies from ATM to native IP environments; in addition, this multi protocol capability also provides a way to converge different types of traffic such as data, voice and video onto one network. MPLS technology also provides some other advantageous features like Traffic Engineering (TE), VPN, Any Transport over MPLS (AToM) and Quality of Service (QoS). This paper will help provide an understanding of how MPLS works and the QoS capabilities it can provide.
History of MPLS
In 1996 a group from Ipsilon Networks introduced a “flow management protocol”, this technology only worked with ATM transmissions and did not become very popular in the...

... The T-TEST
1.0 INTRODUCTION
The t-test was developed by W. S. Gossett, a statistician employed at the Guinness brewery. However, because the brewery did not allow employees to publish their research, Gossett's work on the t-test appears under the name "Student". The t-test is sometimes referred to as "Student's t-test." Gossett was a chemist and was responsible for developing procedures for ensuring the similarity of batches of Guinness. The t-test was developed as a way of measuring how closely the yeast content of a particular batch of beer corresponded to the brewery's standard.
And the same statistical methodology that compares a particular batch of beer to a standard can be used to compare how different any two batches are from each other. The test can be used to compare the yeast content of two kegs of beer brewed at separate times. Extending this into the realm of social phenomena, this methodology was used to address questions such as whether SAT preparation courses improve test scores or not and one of the advantages of the t-test is that it can be applied to a relatively small number of cases. It was specifically designed to evaluate statistical differences for samples of 30 or less.
2.0 DEFINITION OF...

...The T-Distribution and T-Test
“In probability and statistics, Student's t-distribution (or simply the t-distribution) is a continuous probability distribution that arises when estimating the mean of a normally distributed population in situations where the sample size is small” (Narasimhan , 1996). Similar to the normal distribution, the t-distribution is symmetric and bell-shaped, but has heavier tails, meaning that it is more likely to produce values far from its mean. This makes the t-distribution useful for understanding statistical behaviors of random quantities. It plays a role in a number of widely-used statistical analyses, including the Student's t-test for assessing the statistical significance of the differencebetween two sample means, the construction of confidence intervals for the differencebetween two population means, and in linear regression analysis.
Statistical significance is “measuring the likelihood that an event occurs by chance” (Statistical Assessment Service, 2000). In statistics, a result is called statistically significant if it is unlikely to have occurred at random. The amount of evidence required to accept that an event is unlikely to have arisen by chance is known as the significance level or p-value: “the p-value measures consistency by calculating the...

...Two-Sample t-Tests
Connie Tyrone
Walden University
August 24, 2013
Two Sample t-Tests
With this assignment, we are told about Martha. Martha wants to see if her relaxing technique which involves visualization will be able to assist people suffering with mild insomnia to fall asleep faster. She randomly selects 20 insomnia patients to participate in her research. She assigns 10 from the group to participate in visualization therapy and 10 from the group receives no treatment. Martha then keeps a record of how long it takes each participant to fall asleep. As follows:
No Treatment (X1) Treatment (X2)
22 19
18 17
27 24
20 21
23 27
26 21
27 23
22 18
24 19
22 22
Our assignment is to respond to the following questions regarding Martha’s research study and her data.
Should Martha use an independent-samples t-test or a related samples t-test? Explain your answer.
Martha should use an independent-samples t-test. The independent-samples t-test is “the parametric procedure used for significance testing of sample means from two independent samples” (Heiman, 2012, p. 122). In Martha’s case, she has chosen 20 patients in which half will receive visualization therapy and half will not.
What are the independent and dependent variables?
The independent variable in this...

...Introduction
Test anxiety is a multidimensional construct that has been defined as the set of phenomenological, physiological, and behavioral responses that accompany concern about possible negative consequences or failure on an exam or similar evaluation. The research study question is, “Do males and females significantly differ on their level of test anxiety?” The topic is a significant problem to students as well as counselors as they endeavor to alleviate the causes of anxiety attacks (gender has been identified as a cause of high test anxiety) during an evaluative situation whose effects are dire to the reduction of GPA on every level of education and academic achievement. According to Fiore (2003), students suffer lower academic achievements due to high test anxiety (worry and emotionality components are intense) bearing in mind that certain types of subjects or disciplines pose greater anxiety levels than others. The main goal for this study is to compare test anxiety responses between males and females among the 41 participants of CSUN. Age range for females is 21 to 50 and males have 22 to 27. It is clear that female students have a higher (SD= 6.9) than male students with (SD=1.5). The skewed age distribution seems to destabilize the results and serves as a valid explanation for either the lower or higher anxiety levels on sex differences.
Literature review...

...Assessing T-tests
To clearly identify what a t-test accomplishes in descriptive statistics it is imperative to understand what a t-test represents. A “t-test is a parametric statistical test for comparing the means of two independent samples” (Plichta & Kelvin, 2013, p. 464). Gosset developed the
t-test for use in quality control at the Guinness Brewery and published his works under the pen name “Student” (Plichta & Kelvin, 2013). T-tests use assumptions related to the underlying variable of study, where it is assumed that the underlying variable is distributed normally (Fagerland, 2012, p. 76). In essence, the t-test examines differencesbetween two groups on a variable of interest.
Research Study Review
Bradley (2012), proposed to study the effects of nurse practitioners (NP’s) utilizing a skin cancer screening tool along with receiving further education on skin cancer assessment and diagnosis. The study was predicated on the Health Promotion Model (HPM), which was selected based on it relevance to the practice of NP’s and their duty to promote healthy behaviors (Bradley, 2012). “Evidence-based research showcased within the HPM can aid NPs in making practical recommendations to reduce skin cancer risk,...

...right conclusions about a drug’s effectiveness and safety. Online advertisers trying to micro-target consumers must be able to detect patterns in the massive amount of clickstream data they gather from the Web. Risk managers on Wall Street, retail buyers choosing this season’s merchandise, environmental scientists, sports analysts, and military strategists all rely on the ability to synthesize data and predict outcomes.
The key to making sense of all the data now at our disposal is statistics. At leading companies, decisions once driven by HiPPOs (the Highest-Paid Person’s Opinion) are increasingly made by conducting experiments that draw on the core skills of statisticians. Rather than relying on gut instinct, businesses now find ways to test hypotheses and use statistical methods to analyze the results, applying the classic scientific method to decision-making.
Big data promises big things—but only if we have people in place who know what to do with it. The United States has led the big data revolution but faces a shortage of the analytical and managerial talent needed to maximize its potential. The McKinsey Global Institute estimates that the US will face a shortage of up to 190,000 professionals with advanced training in statistics and machine learning (“data scientists”) within six years. But more broadly, another 1.5 million executives and analysts will need enough proficiency in statistics to work closely with data scientists to design...

...T-test for Two Independent Samples
* This test is used when only two unrelated groups are being compared and the measurements are either interval or ratio. The two groups may or may not have the same number of samples.
* The t-test for two independent groups involves testing whether or not there is a significant differencebetween the population means of the two groups.
Consider a study wherein the effectiveness of banana leaves as an organic wrapper was compared to that of aluminum foil. The number of bacterial colonies in rice wrapped in the two kinds of food wrappers was measured after 12 hours at room temperature.
Treatment | Number of Bacterial ColoniesReplicates |
| 1 | 2 | 3 |
Banana Leaves (Experimental) | 4 | 8 | 7 |
Aluminum Foil (Control) | 5 | 3 | 7 |
The main steps in analyzing and interpreting the data are:
a. Set up and test the appropriate statistic.
b. Formulate and interpret your conclusion.
The appropriate test statistic is a t-test for two independent samples. The following procedure is used:
1. State the null hypothesis to be tested.
HO: μA= μB or μA- μB=0
* There is no significant differencebetween the numbers of bacterial colonies present in cooked rice wrapped with aluminum foil.
2. State the...

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