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Statistics
The reason we use moving averages in the first place is that a lot of time-series data is noisy; due to errors in data collection or random fluctuations in the real-world phenomenon, the data jumps...
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Statistics
Let's consider each statement in turn. "It is good practice to include a measure of expected forecast error with any forecast."That one is clearly true. You always want to include error measures in...
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Math
The one-way analysis of variance allows us to compare the values of parameters (often means) between groups. The assumptions to perform an ANOVA test are that the samples are taken from normal...
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Social Sciences
i) One group pre-test/post-test design Here, the experiment is carried out on only one group. The main advantage to having one group is that variability between individuals' results in the...
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Statistics
The analysis of statistics may possibly be considered art--"the expression or application of human creative skill and imagination"--since it can sometimes involve a creative manipulation of...
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Math
30 cards are selected from a deck 1) without replacement 2) with replacement. We wish to know the chance of getting at least one ace. 1) Each time we select a card, it is either an ace or not. The...
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Statistics
A U.S. travel center survey report states that Americans stayed an average of 7.5 nights when they went on vacation. The sample size is 1500. The point estimate of the population mean is the...
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Math
Using the fact the expected value operator E(X) is linear we have that `E[g(X) ] = g(E[X])` if `g(x)` is a linear function. In this case we are given that `g(x) = a` so that `E[g(X)] = g(E[X]) =...
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Math
` `Out of the first 30 pilot samples of `n=100` items per population/batch tested for nonconformity, 95 out of the 30 x 100 = 3000 items were found to be defective. From these pilot data then, the...
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Math
We have that the random variable `X` is such that `X ~`~ Pois(`lambda`) where the mean is given by `lambda=5` . We would like to know the expected value of the random variable `Y = 2^X` Using the...
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Math
The confidence intervals given will be of the form `hat(p) pm z_(1-alpha/2)sqrt((hat(p)(1-hat(p)))/n)` where `z_(1-alpha/2)` is the 100(alpha/2)th percentile of the standard Normal distribution....
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Math
The "heures de vie" or "lifetime in hours" of bulb 10 is, from the table 12 hours. Consider the lifetimes in hours `x_i` `(i = 1,2,...,20)` of the other bulbs 1-20 (excepting bulb 10). The average...
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Statistics
In all of these cases, we are doing some sort of test. We are asking a yes or no question and trying to answer it with our test. In Option 1, we ask if Mary is pregnant. In Option 2, we ask if...
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Math
There are data for each of the three seasons so we should include this in the frequency table and histogram to give all the information. i) A frequency table is a table giving the number of...
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Math
If you wish to carry out a linear regression then create a new variable `x_1 = sin(x-pi)` and carry out the regression of `y` on `x_1` in the usual way, ie fit `y = alpha + betax_1` using...
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Math
We have the paired fuel consumptions (in miles/gal) for each car: city 18 22 21 21 highway 26 31 29 29 It is well known that fuel consumption in the city is worse...
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Math
Given the critical values for 96th and 97th percentiles `Phi^(-1)(0.96) = z_(0.96) = 1.751` and `Phi^(-1)(0.97) = z_(0.97) = 1.881` use 'linear interpolation' to find the 96.4th percentile...
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Social Sciences
When you are looking balance, such as in a statistical graph, and you are looking at symetrical balance you are looking at a graph that has a even number of people before and after the mean. This...
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Social Sciences
When you are designing a research experiment you want to first have your research question and your research hypothesis. What do you expect to find when you are looking at subjects managing...
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Math
The sample taken is a simple random sample (srs) so is representative of the population as a whole. If 1139 out of the 1201 Americans sampled were found to live in neighborhoods with acceptable...
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Math
A) A large sample size is necessary in order to apply the Central Limit Theorem and assume Normality. B) The mean of the ages the individuals would like to live was found to be 87.9 and the...
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Math
Denote the observations `x_i`, `i = 1,2,3,...,10` Then the mean `bar(x)` is given by `bar(x) = sum_1^10 x_i/10 = 70.5` and the standard deviation is given by `sd(x) = sqrt(V(x)) = sqrt(sum_1^10...
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Math
Denote the (binary - value 0 or 1) observations from the two populations `x_i` , `i=1,2,...,n_x` and `y_j`, `j=1,2,...,n_y` where `n_x = 280` and `n_y =350`. We are given that `sum_i x_i = 132`...
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Social Sciences
The NIBRS is based on the collection of data from the records management systems of federal, state and local law enforcement agencies. The incidents and arrests that are included into the national...
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Health
Health data can be divide into two types: retrospectively and prospectively collected. Retrospective/historical studies are sometimes referred to as observational studies. However, some...
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Statistics
The question has been edited as you can ask only one question at a time. To determine the mean from the given frequency table first determine the mid point of each interval. interval...
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Statistics
Validity refers to the point up to which the test that is being taken is actually testing and measuring what is supposed to. There is no specific definition other than this, considering that the...
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Public Health
A result in data analysis is said to be statistically significant if we are 95% confident, say, that the effect we have observed through analysis is a real one and not one that is manifested by...
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Statistics
A person makes a Type I error when they rejected a null hypothesis that could possibly be true. In this case, the politician is saying that he will certainly win the election. Of course, he is...
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Public Health
When testing a hypothesis it is very important to be clear about what measure is actually of interest and what target population it applies to. Often when we collect data we cannot get directly at...
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Statistics
The most likely answer is that this data would be nominal. Depending on how the political scientist was gathering the data, it could conceivably be ordinal or even interval. But this is much less...
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Statistics
When you are talking about type 1 errors you are looking at a statistical term that means that after running a statistical analysis you have rejected a null hypothesis (the hypothesis that states...
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Statistics
Correlational data cannot tell us that causation has occurred. We should also note, though, that correlation does not mean that causation has notoccurred. All that correlation can tell us is that...
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Statistics
The reason for this is that statistics can easily be manipulated to tell a story that a particular source wants them to tell. Therefore, you need to have evidence from a source that is not trying...
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Math
First add the total minutes tardy upfor the whole week for each of the faculty positions. mins tardy pay per min (Rs.) cost per week (Rs.) Lecturers 91...
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Statistics
A concept is simply an idea. It is something that is fairly vague and it can be difficult to understand how to measure the concept. A variable is much more specific and concrete. It is a...
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Statistics
This question lacks specifics. So, my answer will have to be somewhat broad. Whenever there is a problem of response rate or missing data, there can be many problems, as you can imagine. Therefore,...