Questions tagged [data-visualization]

Constructing meaningful and useful graphical representations of data. (If your question is only about how to get particular software to produce a specific effect, then it is likely not on topic here.)

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114
votes
4answers
33k views

Assessing approximate distribution of data based on a histogram

Suppose I want to see whether my data is exponential based on a histogram (i.e. skewed to the right). Depending on how I group or bin the data, I can get wildly different histograms. One set of ...
201
votes
4answers
332k views

How to interpret a QQ plot

I am working with a small dataset (21 observations) and have the following normal QQ plot in R: Seeing that the plot does not support normality, what could I infer about the underlying distribution? ...
77
votes
4answers
25k views

How to visualize what canonical correlation analysis does (in comparison to what principal component analysis does)?

Canonical correlation analysis (CCA) is a technique related to principal component analysis (PCA). While it is easy to teach PCA or linear regression using a scatter plot (see a few thousand examples ...
98
votes
1answer
79k views

Interpreting plot.lm()

I had a question about interpreting the graphs generated by plot(lm) in R. I was wondering if you guys could tell me how to interpret the scale-location and leverage-residual plots? Any comments ...
46
votes
3answers
68k views

Suppression effect in regression: definition and visual explanation/depiction

What is a suppressor variable in multiple regression and what might be the ways to display suppression effect visually (its mechanics or its evidence in results)? I'd like to invite everybody who has ...
54
votes
7answers
55k views

Graph for relationship between two ordinal variables

What is an appropriate graph to illustrate the relationship between two ordinal variables? A few options I can think of: Scatter plot with added random jitter to stop points hiding each other. ...
34
votes
2answers
11k views

Is there a boxplot variant for Poisson distributed data?

I'd like to know if there is a boxplot variant adapted to Poisson distributed data (or possibly other distributions)? With a Gaussian distribution, whiskers placed at L = Q1 - 1.5 IQR and U = Q3 + 1....
34
votes
2answers
53k views

Interpretation of plot (glm.model)

Can anyone tell me how to interpret the 'residuals vs fitted', 'normal q-q', 'scale-location', and 'residuals vs leverage' plots? I am fitting a binomial GLM, saving it and then plotting it.
33
votes
3answers
25k views

What distribution does my data follow?

Let us say that I have 1000 components and I have been collecting data on how many times these log a failure and each time they logged a failure, I am also keeping track of how long it took my team to ...
9
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3answers
7k views

Transfer function in forecasting models - interpretation

I am occupied with ARIMA modelling augmented with exogenous variables for promotional modelling purposes and i have hard time explaining it to business users. In some cases software packages end up ...
7
votes
2answers
4k views

How to use boxplots to find the point where values are more likely to come from different conditions?

I have plotted some data using box plots. I am comparing Condition 1 (left) and Condition 2 (Right) values. My aim is to find a point at which we make a decision where the value changes from point ...
32
votes
3answers
12k views

Visualizing a million, PCA edition

Is it possible to visualize the output of Principal Component Analysis in ways that give more insight than just summary tables? Is it possible to do it when the number of observations is large, say ~...
34
votes
3answers
3k views

Datasets constructed for a purpose similar to that of Anscombe's quartet

I've just come across Anscombe's quartet (four datasets that have almost indistinguishable descriptive statistics but look very different when plotted) and I am curious if there are other more or less ...
3
votes
2answers
1k views

Can I analyze or model a conditional correlation?

In my research I'm looking at the correlation between self-harm and aggression (both continuous). Now, I also have some variables (e.g. depressive symptoms; also continuous) which I do believe ...
43
votes
2answers
59k views

PP-plots vs. QQ-plots

What is the difference between probability plots, PP-plots and QQ-plots when trying to analyse a fitted distribution to data?
21
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2answers
36k views

What does an Added Variable Plot (Partial Regression Plot) explain in a multiple regression?

I have a model of Movies dataset and I used the regression: ...
34
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4answers
58k views

What test can I use to compare slopes from two or more regression models?

I would like to test the difference in response of two variables to one predictor. Here is a minimal reproducible example. ...
48
votes
3answers
77k views

How to visualize a fitted multiple regression model?

I am currently writing a paper with several multiple regression analyses. While visualizing univariate linear regression is easy via scatter plots, I was wondering whether there is any good way to ...
24
votes
4answers
25k views

Which is the best visualization for contingency tables?

Which is best plot, from statistical standpoint, to show a contingency table, which is typically being analyzed by chi-square test? Is it a dodged barplot, stacked barplot, heatmap, contour plot, ...
11
votes
4answers
45k views

How to visualize independent two sample t-test?

What are the most accepted ways to visualize the results of an independent two sample t-test? Is a numeric table more often used or some sort of plot? The goal is for a casual observer to look at the ...
25
votes
6answers
9k views

What are good data visualization techniques to compare distributions?

I am writing my PhD thesis and I've realized that I rely excessively in box plots in order to compare distributions. Which other alternatives do you like for achieving this task? I'd also like to ask ...
26
votes
3answers
12k views

Visualizing Likert Item Response Data

What are good ways to visualize set of Likert responses? For example, a set of items inquiring about the importance of X to one's decisions about A, B, C, D, E, F & G? Is there something better ...
58
votes
12answers
18k views

Software needed to scrape data from graph [closed]

Anybody have any experience with software (preferably free, preferably open source) that will take an image of data plotted on cartesian coordinates (a standard, everyday plot) and extract the ...
31
votes
4answers
4k views

Visualising many variables in one plot

I'd like to show how the values of certain variables (~ 15) change over time, but I'd also like to show how the variables differ from each other in each year. So I created this plot: But even when ...
14
votes
2answers
16k views

QQ plot does not match histogram

I have a histogram, kernel density and a fitted normal distribution of financial log returns, which are transformed into losses (signs are changed), and a normal QQ plot of these data: The QQ plot ...
13
votes
2answers
16k views

Box-and-Whisker Plot for Multimodal Distribution

Can I use box-and-whisker plots also for multimodal distribution or only for unimodal distribution?
10
votes
2answers
3k views

How to represent kWh usage by year against average temperature?

Just for fun, I want to chart my monthly household power consumption year-over-year. However, I wish to include some reference to monthly temperature so I can determine if my home or behavior is ...
10
votes
3answers
7k views

How to extract information from a scatterplot matrix when you have large N, discrete data, & many variables?

I'm playing around with the breast cancer dataset and created a scatterplot of all attributes to get an idea for which ones have the most effect on predicting the class ...
15
votes
5answers
2k views

Removing extraneous points near the centre of a QQ-plot

I'm trying to plot a QQ-plot with two data sets of about 1.2 million points, in R (using qqplot, and feeding the data into ggplot2). The calculation is easy enough, but the resulting graph is ...
70
votes
3answers
134k views

How to actually plot a sample tree from randomForest::getTree()? [closed]

Anyone got library or code suggestions on how to actually plot a couple of sample trees from: getTree(rfobj, k, labelVar=TRUE) (Yes I know you're not supposed ...
55
votes
6answers
65k views

How to determine best cutoff point and its confidence interval using ROC curve in R?

I have the data of a test that could be used to distinguish normal and tumor cells. According to ROC curve it looks good for this purpose (area under curve is 0.9): My questions are: How to ...
43
votes
4answers
43k views

Would PCA work for boolean (binary) data types?

I want to reduce the dimensionality of higher order systems and capture most of the covariance on a preferably 2 dimensional or 1 dimensional field. I understand this can be done via principal ...
32
votes
2answers
83k views

Interpretation of biplots in principal components analysis

I came across this nice tutorial: A Handbook of Statistical Analyses Using R. Chapter 13. Principal Component Analysis: The Olympic Heptathlon on how to do PCA in R language. I don't understand the ...
19
votes
4answers
25k views

Visualizing Likert responses using R or SPSS

I have 82 respondents in 2 groups (43 in Group A and 39 in Group B) that completed a survey of 65 Likert questions each ranging from 1 – 5 (strongly agree - strongly disagree). I therefore have a ...
29
votes
6answers
10k views

Problems with pie charts

There seems to be in increasing discussion about pie charts. The main arguments against it seem to be: Area is perceived with less power than length. Pie charts have very low data-point-to-pixel ...
17
votes
2answers
5k views

Alternative to sieve / mosaic plots for contingency tables

I once stumbled across a type of plot for categorical data (i.e., contingency tables) on the internet, which I really liked, but I've never found it again, and I don't even know what it's called. It ...
12
votes
1answer
28k views

Graphing a Probability Curve for a Logit Model With Multiple Predictors

I have the following probability function: $$\text{Prob} = \frac{1}{1 + e^{-z}}$$ where $$z = B_0 + B_1X_1 + \dots + B_nX_n.$$ My model looks like $$\Pr(Y=1) = \frac{1}{1 + \exp\left(-[-3.92 + 0....
68
votes
3answers
77k views

When are Log scales appropriate?

I've read that using log scales when charting/graphing is appropriate in certain circumstances, like the y-axis in a time series chart. However, I've not been able to find a definitive explanation as ...
16
votes
2answers
8k views

Is it possible to create “parallel sets” plot using R?

Thanks to Tormod question (posted here) I came across the Parallel Sets plot. Here is an example for how it looks: (It is a visualization of the Titanic dataset. Showing, for example, how most of ...
22
votes
3answers
19k views

How to present box plot with an extreme outlier?

I could use some guidance about presenting some data. This first plot is a case-control comparison for the cytokine IL-10. I've manually set the y axis to include 99% of the data. The reason I set ...
10
votes
2answers
1k views

Does Simpson's Paradox cover all instances of reversal from a hidden variable?

The following is a question about the many visualizations offered as 'proof by picture' of the existence of Simpson's paradox, and possibly a question about terminology. Simpson's Paradox is a fairly ...
11
votes
1answer
997 views

Box plot notches vs. Tukey-Kramer interval

The "notch" help document (or original text) from boxplot in 'R' gives the following: If the notches of two plots do not overlap this is ‘strong evidence’ that the two medians differ (Chambers et ...
5
votes
3answers
3k views

How to plot a learning curve based on a sequence of date stamped successes and failures?

I have data on results of surgical operations: date of operation (in YYYY-MM-DD format) result of operation (0 for successful operation, 1 for unsuccessful operation) Date is usually used only for ...
66
votes
9answers
18k views

How to visualize what ANOVA does?

What way (ways?) is there to visually explain what is ANOVA? Any references, link(s) (R packages?) will be welcomed.
50
votes
5answers
278k views

R - QQPlot: how to see whether data are normally distributed

I have plotted this after I did a Shapiro-Wilk normality test. The test showed that it is likely that the population is normally distributed. However, how to see this "behaviour" on this plot? ...
50
votes
3answers
38k views

How do I find peaks in a dataset?

If I have a data set that produces a graph such as the following, how would I algorithmically determine the x-values of the peaks shown (in this case three of them):
10
votes
3answers
1k views

First quick glance at a dataset

Please pardon my ignorance, but... I keep finding myself in a situation, where I'm faced with a bunch of new data I managed to find. This data usually looks something like this: ...
31
votes
3answers
7k views

What is the proper name for a “river plot” visualisation [duplicate]

In a famous plot, Charles Minard visualised the losses of the French Army in the Russian campaign of Napoleon: (another nice example is this xkcd plot) Is there a canonical name for this type of ...
15
votes
8answers
3k views

Alternative graphics to “handle bar” plots

In my area of research, a popular way of displaying data is to use a combination of a bar chart with "handle-bars". For example, The "handle-bars" alternate between standard errors and standard ...
25
votes
9answers
23k views

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