Hi all,

I'm running the quantile regression and trying to plot the coefficients and confidence intervals of four independent variables (yeaedu, sex, union, unimem).

The data a .dta file, but I used as_factor to convert data before running the regression.

**My codes:**

bri0 = read.dta("britearn.dta")

bri0.1 = as_factor(bri0,only_labelled = TRUE)#quantile regression

model.bri.q = rq(lrehrwge ~ yeaedu + sex + union + unimem

- seniorit + yeactexp + race + mastat
- jbsect + region,

data = bri0, tau = seq(0.1, 0.9, by=0.1),

na.action = na.exclude)

summary(model.bri.q)

**My data file:**

https://redirect.is/qhnxri8

**My errors are:**

Warning messages:

.... Solution may be nonunique

```
1: In summary.rq(xi, U = U, ...) : 37 non-positive fis
2: In summary.rq(xi, U = U, ...) : 9 non-positive fis
3: In summary.rq(xi, U = U, ...) : 2 non-positive fis
4: In summary.rq(xi, U = U, ...) : 9 non-positive fis
5: In summary.rq(xi, U = U, ...) : 5 non-positive fis
6: In summary.rq(xi, U = U, ...) : 7 non-positive is
```

So, my questions are:

- How did I get these errors?
- How can I plot the effects of
**only**four variableson the dependent variable (most of the rest are categorical variables, I don't want to plot them)?**yeaedu + sex + union + unimem**

I'm a beginner user of R, so I hope that you can help me to resolve my problem well.

Thank you so much!