Questions tagged [descriptive-statistics]

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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15 views

Modifiable Areal Unit Problem

According to Wikipedia The modifiable areal unit problem (MAUP) is a source of statistical bias that can significantly impact the results of statistical hypothesis tests. MAUP affects results when ...
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Degree of freedom [duplicate]

Why do we use degree of freedom while dealing with samples(e.g. while calculating t statistic and sample variance, we divide by $ n-1 $ degree of freedom, but while calculating z score and population ...
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Comparing frequencies in two groups between two time periods

I've got data that are essentially set up in two 2x2 frequency tables. I have frequencies that males and females disperse or recruit to a given region. I am interested if the proportion of sexes that ...
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What do you call a weighted summary statisitc?

I want to present a summary statistic of 20+ simultaneous classes where each class has an AUC-statistic that I would like to describe in a single statistic, e.g.: ...
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1answer
15 views

Is there a standard terminology for expressing percentages of variations when computed in 2 different ways?

I have a bunch of measurements, say .71 .75 .70 .79 of a certain quantity. The range of these measurements is .79-.71 = .08 The percentage of variation can be expressed in 2 ways: (1) range/...
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1answer
49 views

Can I use anova on values in decibel (logaritmic)?

I'm doing a project where I'm measuring outdoor sound in different spots. I've repeated the measurement 3 times at every spot on different days (with different weather etc). I measure every spot for ...
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What SPSS procedure to follow in order to measure each independent group's dependent variable's mean? [closed]

Let me get into things briefly. I've got two independent groups (samples): A) one as experimental and one as B) control group. Each sample has variables X and Y. If more precisely, X is some ...
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23 views

Descriptive statistics: T-test & Wilcoxon test [closed]

I am a beginner in R and I would like to compute descriptive statistics (mean & variance) for a variable of my dataset by groups (defined by another variable) for two different periods. Following ...
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Adjusting mean for review scores

I have a collection of reviewers who are rating applications. Each application is reviewed by at least two people and they give a score between 0 and 50 among various criteria. Looking at the mean ...
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1answer
14 views

Is there a convention for how to handle data points that fall on the fences when determining outliers?

If I have a data set where a given measurement is equal to Q1 - 1.5(IQR), is there a convention for how to handle this? Should this be considered an outlier?
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1answer
44 views

How to write descriptive statistics?

I am using logistic regression to look at the association between plaque and smoking, with adjustment for a bunch of potential confounders. In the descriptive statistics section, is it normal practice ...
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Find Q1 and Q3 from median and IQR

A study gives the following: $n = 67$ mean = 73 sd = 68 median = 55 IQR = 66 Is it possible from this information to get the actual Q1 and Q3 values? I used the $n$, mean & sd to get 95% ...
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Pearson's Correlation for percentage data (observations within variable sum up to 100%)

Suppose the following dataset: ...
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mean “confidence interval” including where nan data is present

I have a question about getting 'confidence interval' lines for where my data lies. Confidence interval may not be the best definition for it it may be more of a "probability" for where the data is I'...
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1answer
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Descriptive statistics for 2 variables grouped by gender with spss

I have 3 variables one categorical gender and the others are the IQBefore and IQAfter which ...
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23 views

Determining outliers

I have a data set containing 12 concentrations with 8 absorbance readings each. From this I did linear regression of three consecutive concentrations and their absorbances and got 10 slopes. I am ...
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9 views

dispersion in Data

do we compare the value of standard deviation value with mean to conclude that data is less dispersed or more dispersed? for example, if the SD value is 754 and the mean is 934, what about dispersion ...
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146 views

What's the added value of SD line over regression line when examining association between 2 variables?

I'm trying to incorporate different practices to use when exploring a new data set. Especially, how to examine the association between two variables. Steps for example (not necessarily by order): ...
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How do you calculate variance for percentages?

I know this seems like a simple questions but I am trying to wrap my head around calculating variance for percentages (e.g. 15%, 16%). I know that 15% is equivalent to 0.15, but when I try to ...
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21 views

Karl Pearson correlation coefficient

How to prove that we can not measure the correlation coefficient between two variables using Karl Pearson correlation coefficient formula when there is a non linear relationship between them?
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What type of ANOVA or T-Test can I use for this data?

I am not very familiar with using statistical treatment and would like to ask for some help. We are conducting a study to test our constructed device and ran an experiment in which its transmitted ...
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21 views

if a very large amout the rows are missing in any perticular column is it appropriate to drop it?

I am dealing with time series data having a large number of columns, in which some of these columns have 95% of misssing values. If I drop these columns and continue will that really affect my model'...
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1answer
19 views

Should I use One-Way ANOVA or Paired T-test in this data? What software can you recommend?

I am a beginner on Statistical analysis and I'm honestly not confident with the tools I'm choosing. I conducted an experiment on measuring a person's pulse rate using our project/ device and compared ...
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Rules/Statistical methods to segment customers into quality groups

Agency has customers who deal with end consumers. End consumers can leave customers reviews based on their experience (Star ratings, text etc). Agency is trying to segregate new/old customers into ...
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How to predict future data using a sample

Is there a statistical tool to create a confidence interval of sorts that instead of trying to pin down the population mean it tries to pin down the mean of a future sample. In the same way that a ...
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50 views

What will be the appropriate statistical test for this design please?

I have a data of: 30 medical students who have rated visibility of 40 brain anatomical structures (each structure has been rated on a Likert scale of 1-5, where 1 corresponds to "not visible" and 5- "...
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21 views

How to best display the distribution of a large dataset with many outliers? [duplicate]

I have a very large data set (~300'000 data points) and a subset of it (6000 data points), which shows the difference of travel time [in seconds] of agents before and after a road closure. I want to ...
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How to determine the accuracy and variance in categorical survey data responses?

I've conducted a survey where I have shown citizens images of transect squares placed in a field. For each image of a transect square, I've asked citizens to i) count the number of beetles (a ...
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1answer
23 views

How to quantify distribution concentration in cdf? [closed]

For example, let's say I have a list of users, each user has its revenue. I can plot the cdf of both user and revenue, to see if there is some concentration, for example, may be 40% user contribute ...
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1answer
26 views

how can I estimate the median without much data?

I have a distribution of particle size, however I do not have the raw data, I only know about the bounds, approximately 33% of the data is less than 2 microns and about 0% is more than 45 microns, ...
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8 views

How to determine correlation strength of relationship determination?

There is a generic rule of thumb with which people determine the strength of correlation i.e. weak, medium, strong or no correlation. Instead of using the rule of thumb is there a way to determine ...
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What is the interpretation of a statistical CL contour *in the case* where the central observed measurement does not belong to the interior?

What is the interpretation of a statistical Confidence Level contour in the case where the central observed measurement does not belong to the interior of the contour ? (you may see below that this ...
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Econometric or statistical method to range variables that explain dependant variable

I want to discuss the degree of explanation of my dependant variable $y$ by some independant variables $x_1$, $x_2$ and $x_3$. I want to be able to say that variable $x_1$ explains for example 10% of ...
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1answer
26 views

compare correlation between two matrices

We have two algorithms that assign a score to the foreground of how well it fits the background. And we want to know which algorithm is closer to human perception. Then we collect an evaluation set ...
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25 views

Why do regression estimates provide lower relative error than averaged values?

I am trying to estimate the per-cell protein concentration for some samples. I have performed a series of protein extractions for each of my samples, with each extraction using an increased (and known)...
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1answer
26 views

My histogram suggests my data is not normally distributed but the stats suggest it is, can i assume normality or not?

I am looking as likelihood to forgive and need to decide what correlation to use to apply this scale to attachment type. My histogram shows a slight positive skew, but the test of normality (...
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1answer
35 views

For PCA, the best axis for the projection of the points is the one who has the minimal or the maximal inertia?

I am learning statistics mainly from a book : Elements de statistique, from three author of the Brussels University. 5th Edition On the PCA chapter, however, I need to read from other sources, ...
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1answer
64 views

Chi Square test or McNemar test?

I've got a set of 1000 patients and I am measuring two different blood values (CRP and IL6) and choosing a categorical cutoff values for both (CRP>10 and IL6 >2). I now would like to know if there is ...
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1answer
20 views

How close the value of correlation coefficient (r) has to be to 1 to call it a strong positive relationship?

I am trying to find the linear relationship between a few variables. If you look at the graph below, it feels like there is a moderate positive correlation. And If I look at the numerical values(...
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Can the ranks of summary statistics discriminate between (shapes of) multiple distributions? (intuition)

TL;DR Can we say the following statement, especially the first part of it? It feels intuitively true: (1) The ranks of summary statistics characterize the overall shape of distributions... (2) ...
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138 views

Sample subset characteristics

Edit: It seems that I have made the question too general, so I will provide a specific example of the type of problem I am trying to solve. I have a database that contains every item that is sold at ...
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1answer
22 views

Correlation matrix: decline in correlation

I performed a correlation matrix with Python. The following variables were included total_equity,net_income,...
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25 views

How do I interpret the paired t-test results?

How do I interpret these results? Which food does the Corvid like best? What does the p-value and t-value mean? Is this test significant? My hypothesis is: H0 Corvids have no preference on food ...
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1answer
14 views

True or False: The pattern of the residuals vs predicted values and the residuals vs a predictor based on a 2nd order model are exactly the same

I'm currently working on an assignment for a course in Statistics and was wondering anyones thoughts on this. My friends and I keep going back and forth on which one it is. I think it's true for the ...
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2answers
209 views

Can IQR ever be larger than standard deviation?

As I understand it the IQR specifies the dispersion of the data by taking the difference between Q3 and Q1 (i.e., the range that the middle 50% of the data lies), while std specifies dispersion using ...
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1answer
41 views

Is this data interval or ratio?

Students at my school can have 0 to n number of absences. We recorded the number of absences of 100 students in Fall 2018 before the intervention. At the beginning of the Fall 2019 school year we ...
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21 views

Calculating the coefficient of variation within pairs

I would like to calculate the coefficient of variation of an assay where I measured each sample in duplicate. I have no statistical background but from my understanding I would need the standard ...
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15 views

Extrapolating from the significant difference between two continuous variables

If we have two continuous variables, the same variable in fact, one before an intervention and the other after, and we then see by a paired t-test that there is a significant difference between the ...
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47 views

Show that t distribution variance doesn't exist when df = 2

When DF = 1, t distribution is just Cauchy distribution whose mean does not exist. $E(T) = E(\frac{Z_1}{\sqrt{Z_2^2}}) = E(\frac{Z_1}{Z_2}) = E(Z_1)E(\frac{1}{Z_2})$ where the second expectation ...
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1answer
87 views

Calculating two standard deviations above the mean

I have a variable a need to find data points which are two standard deviations above the mean. Example, let say we have: 2, 3, 4, 120, 5. Sample mean=26.11 Stan.deviation=52.11 I have been ...

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