2019年3月28日 · In this post we describe how to interpret a QQ plot, including how the comparison between empirical and theoretical quantiles works and what to do if you have violations. You may also be interested in how to interpret the residuals vs leverage plot, the scale location plot, or the fitted vs residuals plot. QQ-plots are ubiquitous in statistics.

QQplot 可以用来判断样本点是否符合任意一种概率分布，其方法就是和前面所讲normal distribution的例子一样，如果怀疑样本点符合某种分布，那么就找出从这样一个分布中抽取相同数目随机数时期望得到的数值，将这些数值与实际的样本点的值放在QQplot中进行比较，如果点的分布接近一条直线就说明，样本点的分布和猜测的分布相同，反之则不同。 最后吐槽一下，知乎的文字编辑功能真是太有限了，有待优化.

2024年11月17日 · Discover how Q-Q plots are a useful visual method to assess normality. Compare observed data to a theoretical distribution like the normal distribution to highlight deviations. Learn to diagnose model fit.

进行数据分析时，都可以从数量（Quantity）、质量（Quality）这两大角度进行分析，简称为QQ模型，也称为QQ模型分析方法。QQ模型是数据分析中一种常用的分析方法。

Q-Q plot of the quantiles of x versus the quantiles/ppf of a distribution. Can take arguments specifying the parameters for dist or fit them automatically. (See fit under Parameters.) A 1d data array. Comparison distribution. The default is scipy.stats.distributions.norm (a standard normal).

2024年1月19日 · A Q-Q plot, short for “quantile-quantile” plot, is used to assess whether or not a set of data potentially came from some theoretical distribution. In most cases, this type of plot is used to determine whether or not a set of data follows a normal distribution.

I made a shiny app to help interpret normal QQ plot. Try this link. In this app, you can adjust the skewness, tailedness (kurtosis) and modality of data and you can see how the histogram and QQ plot change. Conversely, you can use it in a way that given the pattern of QQ plot, then check how the skewness etc should be.

2020年8月4日 · A better way to determine the mixing proportions and relative SDs would be to fit a Gaussian mixture model. In R, that can be done with the Mclust package, although any decent statistical software should be able to do it. I demonstrate a basic analysis in my answer to How to test if my distribution is multimodal?

2012年12月13日 · qqnorm is a generic function the default method of which produces a normal QQ plot of the values in y. qqline adds a line to a “theoretical”, by default normal, quantile-quantile plot which passes through the probs quantiles, by default the first and third quartiles.

What is a QQ plot? A QQ plot; also called a Quantile Quantile plot; is a scatter plot that compares two sets of data. A common use of QQ plots is checking the normality of data. This is considered a normal qq plot, and resembles a standard normal distribution through the reference line and value distribution.