Descriptive statistics summarize features of a sample, such as mean and standard deviations, median and quartiles, the maximum and minimum. With multiple variables, may include correlations and crosstabs. Can include visual displays - boxplots, histograms, scatterplots and so on.

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Relationship between central moments and dependent variable

I was given the task to determine the effects of several statistics on (electricity) derivative prices. Suggestions were variance, skewness, kurtosis to start with. I have a pretty good idea how to ...
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19 views

Measuring change in performance over time

I have two performance scores for multiple companies over a ten year period (10 sets of scores, one set for each year). Which would be the best method to test the hypothesis that one score has dropped ...
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18 views

Relation between precision, recall and sample size

I have a large data set for binary classification problem. Now in order to fit model to data I have been trying modeling using various sample size. For each sample size I gets a different precision ...
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1answer
37 views

Best fit with GLM in R

I'm trying to know what is the best GLM fit with this simple dataset and tests in R: ...
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24 views

Central Tendency measure for Response time?

Assume a classic scenario where there are bunch of employees and everybody are given tasks to complete on a regular basis and those tasks may or may not have deadlines. Objective is to to find a ...
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17 views

How do you treat replicates for ordinal data?

Let's say I have a set of tumors, and I ask two pathologists to rate it on a scale of 1 through 5, 1 being the most benign, and 5 being the most aggressive. The data sends up looking like: ...
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13 views

Finding proper cut off for filtering?

I had a set of data (149876 rows and 1200 columns)and I have found outliers points for each row. Now I want to determine a proper threshold for filtering my outliers. The distribution of my data is ...
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14 views

Homogeneity-Heterogeneity of a variable distribution

I have a graph that represents the distribution of a variable in my population (% of body fat in the x-axis and the frequency in the y-axis) My question is how can i know if the distribution of the ...
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1answer
30 views

Basic & quick question about confidence interval (novice)

I'm writing a research proposal and I need to include an estimation of what kind of sample size would be adequate. I've used a calculator, and I get the result that with a 95% confidence interval and ...
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43 views

How can I determine whether a change is statistically significant ONLY based on confidence intervals and points of estimate?

The table above shows the proportions (%) of a given country's population that have experienced theft from vehicles each year along with respective confidence limits. How can I tell if a change ...
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28 views

Issues with showing total N and missing data, total observations on Cox model

I'm trying to get an article which tries to assess if there was a higher risk of a condition being longer in a year when compared to a previous year. I' m not getting a lot of help, so I sincerely ...
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10 views

How to best analyze a Semantic Differential?

1) How do I code the data gathered from the dependent var (PQ) below in excel for analysis in SPSS? I know how to run an ANOVA afterwards. N=60; Legend: 1 and 7: (extremely), 2 and 6: (moderately), ...
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17 views

Research Design Strategy

The total number of participants in a study is 70. This sample is divided into two groups. Group A (35 participants) and Group B (35 participants). The purpose of the study is to investigate the ...
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16 views

number of questionnaires and sample size

Is there any correlation between number of questionnaires used in a study and the sample size in order to obtain accurate measurement?
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6 views

Are crossplots of closed-sum attributes from independent analyses valid?

Some geochemistry papers that I have read contain crossplots of compositional components that resulted from different analyses of a rock sample. For example, one is the percent volume of TiO$_2$ ...
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24 views

Statistic for deviation from uniform distribution

I am analyzing eye movement patterns. The data is from an evenly arranged three-by-three pattern of squares. I have, for each of the nine squares, the total time that a person was looking at it ...
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2answers
25 views

How to interpret SPSS p-value for one tailed tests

Suppose H0 = Mean 1 - Mean 2 > or = 0 and HA = Mean 1 - Mean 2 < 0. We do an unpaired t-test in SPSS to get our p-value. The SPSS p-value is 0,534. This P-value is two tailed, so we have to devide ...
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1answer
81 views

Error in the design of an experiment

Suppose that we have a population with a subpopulation that exhibits a certain characteristic. We are interested in the performance of a group of people from the population on a group test. The ...
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2answers
45 views

Most probable value given a dataset

Forgive my high-school level mathematics but say I have the following dataset: [2, 3, 4, 5, 6, 6.5, 7, 7.5, 8.5, 9.5] I want to know what value is most likely to ...
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1answer
27 views

How to calculate the probability p of a binomial distribution using the mean?

You are given following elements about a binomial distribution: n = 15 $\overline{x} = 2$ What is the value of the probability $p$? I mean this $p$: My guess is: $p = ...
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82 views

Anscombe-like datasets with the same box and whiskers plot (mean/std/median/MAD/min/max)

EDIT: As this question has been inflated, a summary: finding different meaningful and interpretable datasets with the same mixed statistics (mean, median, midrange and their associated dispersions, ...
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1answer
84 views

“Inverse” Q-Q plot?

Suppose we have two real-valued random variables $X,Y$. Let $cdf_X$ and $cdf_Y$ be the corresponding cumulative distribution functions. We are interested in graphically comparing the distributions ...
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9 views

Hypothesis test design taking into account follow-up segmentation studies

Suppose I want to have a simple test with one treatment group and one control group. Let's assume the treatment for the treatment group is increasing a quantity $X$ by $10\%$. I have two questions: ...
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1answer
22 views

How to calculate theoretical quantiles of an odd dataset?

In order to calculate a set of theoretical quantiles I usually apply the following method: $\frac{1}{2. N} + \frac{x}{N}$ so here this makes: $\frac{1}{24} + \frac{6}{12}$ $\frac{1}{24} + ...
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1answer
33 views

Calculate the mean of the minimum of any k samples

Given a fixed list of N numbers from an unknown distribution, and a k (k <= N), say we ...
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2answers
49 views

How to calculate the probability of making a type 2 error?

Knowing the probability of having a type 1 error equals to $\alpha$ (significance). I think it might be incorrect to tell that if $\alpha = 20 $ the chances of making a type 2 error are equal to 80%. ...
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2answers
189 views

The more degrees of freedom for a student-t distribution the flatter? If yes, why?

Assume we have a student-t distribution. Is the following statement true: "The more degrees of freedom we have the flatter the curve" ? If yes/no why?
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13 views

Sampling from an Isometric Multivariate Gaussian

I implemented a Multivariate Gaussian Distribution. I know that it will be isometric, so the covariance matrix will contain solely diagonal values. As standard way to sample from a Multivariate ...
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17 views

I need to establish performance metrics using data I gathered in a trial period

I believe this can be done using statistics but how to, I do not know. I hope you can help me... We have a new workflow and I was tasked to set the performance metrics for it. So what I did was I ...
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15 views

Statistical test to assess the strength of the assertion “time series' values stayed the same”

The title somewhat gave my question away, but here goes... I have a time series of values covering a certain time span... If I chart it, I can visually conclude values roughly stayed the same. That ...
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16 views

Understanding the proof of F-test

I am having a difficult time understanding the proof of the F-test. What do the second and third line stand for? What are these lines specifically telling?
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1answer
37 views

How to calculate quantiles?

Could someone please show(!) and explain step-by-step how to calculate the theoretical quantiles for the following normally distributed dataset: {1,1,2,2,2,3,3,5,8,14,24,40} Given this table: ...
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1answer
79 views

How should I interpret the results of corrplot (variable correlations plot)?

I am trying to look at correlation between different variables. I used MATLAB's corrplot function and got the attached results. The function's documentation ...
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7 views

Number of Questionnaires and sampling frame

Do the number of questionnaires used in a study affect the number of participants in a sample frame? If so, how do I estimate the sample size based on the number of questionnaires (during pre-test, ...
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1answer
29 views

Should I still need to use Factor Analyses for the scales used in previous papers?

Let's say, I used two scales that measures - 1. Perception of eco-label and 2. Perception of eco-brand. Each of them have 4 items (questions). Items are measured on 7 point-likert type questions. ...
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20 views

Statistical Method for Normalization of Data

I collected data using a pre-test instrument to capture baseline emotions (two dimensions: valence and arousal) of participants. The two dimensions in the questionnaire range from calm to excited ...
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1answer
69 views

Remove measured distribution from another distribution

Take a particle beam as an ensemble of many particles. Assume two independent random variables $X_\beta$ and $\delta$ that add up to the horizontal position $X$ of a particle: $$ X = X_\beta + D_x ...
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2answers
43 views

Quasi and True Experiments

If subjects are recruited using a convenience sample to take part in a study, and each participant is then randomly assigned to either treatment condition, A and B. (i) Will my result be ...
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1answer
24 views

Same estimate of least squares regression equation

This was one of the question in my test which I was not able to attempt. Question: Let $\left\{ \left. \left(x_{i,1}, x_{i,2}, \ldots, x_{i,d}, y_i\right) \; \right\rvert \; i = 1, \ldots, n ...
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1answer
48 views

Empirical formula- 68%, 95.5%, & 99.9% of scores

I'm having trouble with some stats questions for my psychological testing paper. Have tried emailing the professor but to no avail. Given the standard deviation of 19.8,Identify the range of scores ...
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1answer
24 views

Count data with three response types

I administered a test to three groups of people. They had to choose the correct answer between four choices provided. Only one choice is correct and the other three are wrong answers. There are forty ...
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1answer
37 views

What type of relationship is in this scatter plot

I am plotting the number of accidents happened daily vs the daily precipitation for Car collision data of New York City for the year 2013 using scatter plot. I found a strange chart which I am not ...
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31 views

Calculating Multiple R-squared from Adjusted R-squared

I need to calculate Multiple R-squared knowing only adjusted R-squared and the number of predictors, not the number of observations within given data. However, I know (1) residual standard error, (2) ...
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1answer
44 views

Explaining correlation matrix calculations

This is the part of my exam preparation. Similar tasks will be provided in my exam paper with extremely limited amount of time. So I need to learn techniques for solving these tasks quickly. Here is ...
3
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1answer
76 views

How to tell a coefficient of variation (C.V.) is high?

I have a group of data series which contain hundreds of values. I've calculated the C.V.s of these data series, but I don't know how I can recognise if they are high or low according to the C.V. ...
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18 views

Trying to get mean and r where two regression equations are given

Use the following regression equations to calculate mean of Y, mean X and $r_{XY}$ $X=-0.4Y+6.4$ $Y=-0.6X+4.6$ My thoughts are that these two are simultaneous equations. The meeting point of these ...
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19 views

What kind of methods do I need to use in order to analyze this kind of health dataset

I've recently been given a dataset with the following variables: -BMI -Type of Therapy (indicated by 1, 2, or 3) -ADH Levels -HIV positive or negative (0,1 dummy variables) -Systolic blood pressure ...
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33 views

Free very basic downloadable printable stats textbook

I volunteer teach a (very) basic stats course at a local medium/high security prison. My intent is just to get across basic ideas so that the inmates can make some contact with that branch of ...
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2answers
115 views

Can a percentile simultaneously refer to the % below or equal to a score and the % above and equal to a score?

I realise there are several definitions of a percentile. Recently I was given the following definition Definition 1- A percentile is the percentage of scores lower than or equal to it I was then ...
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1answer
71 views

Why use a “truncated mean” (aka “trimmed mean”)?

NB: In this post, I will use the abbreviation $TM_P$ to stand for a symmetric truncated (or trimmed) mean that discards the largest and smallest $P/2$ percent of the data. In fact, for concreteness I ...