Error in approx(nintv, cvals[nintl:ninth, tintl, i], n = max(nintv) - : need at least two non-NA values to interpolate

Asked Apr 08 '20 at 14:13

Active Jul 18 '21 at 13:34

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I am trying to apply the second generation panel unit root tests (CIPS test) using function cipstest() of package plm in R.

I am getting this error:

Error in approx(nintv, cvals[nintl:ninth, tintl, i], n = max(nintv) - : need at least two non-NA values to interpolate.

There are no missing values in my data. Could you help me with this subject?

library("plm")
df1 <- pdata.frame(df, index = c("country", "year"), drop.index = TRUE)
cipstest(df1$AVA, lags = 2, type = "trend")

edited Jul 18 '21 at 13:34

Helix123

asked Apr 08 '20 at 14:13

Ozge

Hi, you might want to add some [reproducible code](https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example) to make it easier to understand the problem and give you an answer. – Duccio A Apr 08 '20 at 14:28
I suspect you do not have enough data points in the time dimension of your panel for the test to be executable. – Helix123 Jul 18 '21 at 13:35

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