Learning goals

• Read, process and manipulate SPSS (or other labelled) data in R while maintaining the labels
• Learn the most common operations on labels
• Enable you to seamlessly work with both R and SPSS so you can split your workflow between the two as you (or your teammates) wish

Overview

Researchers often work with both R and SPSS, so it is helpful to work with .sav files in R. While working with SPSS data in R is not particularly hard, it can be quite confusing to chose the right approach. There are several packages available on CRAN that offer more or less the same functionality, but some of them don’t work well in conjunction with each other and most of them don’t offer all the features you might need. This building block is intended to guide you through the tasks you will find yourself doing most often when working with SPSS data in R.

Required packages

For this workflow, we’ll need two packages: the ubiquitous tidyverse as well as sjlabelled.

There are several packages on CRAN that allow reading .sav files and handling labelled data. haven (co-authored by Hadley Wickham) and labelled seem to be the most well-maintained ones, but they both lack some crucial functions, like converting factors to numeric. sjlabelled is yet another package that does provide this functionality. While haven and labelled work great in conjunction with each other, it is not recommended combine them with sjlabelled, as there are several name conflicts, which can make things confusing. Hence, we will be only using sjlabelled in this tutorial.

Importing and inspecting labelled data

To read a .sav file, we can use read_spss() from the sjlabelled package. Categorical variables that SPSS stores as numbers are automatically converted to factors. Note that at this point the displayed levels will still be numbers. In version 1.2.0 of sjlabelled, which was the latest version when this tutorial was written, read_spss() returns a data.frame. We recommend to convert to a tibble right away:

For this tutorial, we’ll work with the efc dataset on informal care. It comes with the sjlabelled package.

SPSS works with both variable labels and value labels. Value labels can be very handy to store relevant metadata. For example, you can store the whole question that the participants got to see.

Manipulating labels

Unlike SPSS, R does not gain any performance by storing categorical data as numbers instead of the actual (character) value. This has the benefit that the data it is more easily readable by a human and makes data manipulation by category more intuitive. We can replace the numeric levels with the actual categories with as_label().

If we want to be safe, we can also smush together the value ID and the value of the factor levels.

The latter variant is not recommended though, as it it a bit tricky to get rid of the numbers in square brackets again.

Assigning labels to data

Storing and reassigning labels

The most common types of data frames, such as tibbles and data.tables should all support variable and value labels. Still, depending on your analysis it can happen that you lose the labels in the process. In that case, you can simply store the labels in a separate object at the beginning of the analysis and re-assign them at the end.

This data frame does not carry any labels anymore, just like a “normal” R dataframe. Let’s try to re-assign the variable labels we stored in a variable. We can use var_labels() and val_labels() to to do that. Both functions accept name-value pairs as arguments, one per variable to be labelled. However, we can splice a named vector to a list of arguments for var_labels() with !!!. !!!variable_labels is equivalent to var1 = label1, var2 = label2, …

Analogously, we can re-assign the value labels:

Now let’s fully re-label the “processed” dataframe. As you saw before, both var_labels() and val_labels() can be used with dplyr syntax. Note that with this syntax, the order of columns doesn’t matter, and we can even reorder them before re-assigning the labels.

Both var_labels() and val_labels() automatically skip variables that are given in the arguments that aren’t present in the dataframe. However, this will produce a warning:

If you don’t want the warning, you can create a makeshift version of any_of() for this case that only considers variables that exist in the dataframe. This blows up the syntax quite a bit, though.

To make things more concise, we can use a convenience function:

If you happen to find a better way to only consider variables that exist in the dataframe, please let us know!

Labeling data

Another operation you might want to do is to label previously unlabeled data. Let’s use mtcars as an example:

Let’s assign the variable labels that are given in the documentation in ?mtcars

We could also assign value labels to vs and am, but let’s leave that for now.

Nominal and ordinal measures

Converting between nominal and ordinal data

SPSS knows two types of categorical measures, nominal and ordinal. In R, this distinction is made with a flag which indicates whether the data is ordered or not. Note that sjlabelled::read_spss() reads all factor columns with this flag set to FALSE, which means you’ll have to retag ordinal variables yourself. To do that, you can use as.ordered()

as.ordered only works on vectors though. To use it on a dataframe, we can define a convenience function that works on selected columns of a dataframe. With the {{ cols }} syntax, we ensure the function supports tidyselect syntax.

We can then perform conditional operations based on the ordered flag:

To convert factors back to unordered (i.e. nominal) ones, you can use:

Quantitative statistics on ordinal data

Sometimes ordinal data is interpreted as numerical data. One example for this is questionnaire data, several related questions are grouped together and the numerical levels are used to perform quantitative statistics. To do this, we need to replace the values of factors with their corresponding numeric level identifier. In sjlabelled, we can do that with the as_numeric() function.

If you want to have the numbers start from 0 or a different value, you can provide as_numeric() with the start.at = argument.

We can now perform statistical operations. By calling rowwise(), we can ensure that the functions are applied per observation/participant and not on the whole column. Let’s compute a custom score that summarizes all positive measures of the care for the elderly:

Export data back to SPSS

After we imported the SPSS file, we can clean and analyze the data as we normally would. Afterwards, we can save it either as a .csv or we can go back to a .sav file. In the latter case we need to go back to the SPSS standard, i.e. keep the variable labels and replace factors with numerical IDs plus corresponding value labels. Conveniently, both can be done automatically in R! This is the only time that we will be using a function that is not part of sjlabelled, but the haven package. We don’t recommend attaching haven with library(), though. Instead we will be calling it with the :: notation. Factor columns will be treated as nominal measures by default, so make sure to flag ordered variables (e.g. with our custom function as_ordered_cols()) before exporting.

sjlabelled has is own function to export .sav files which is a wrapper for haven’s write_sav(). It is, however, less flexible in practice, so haven’s version is recommended.

If you want to export the numeric version of the dataframe, make sure to convert it to factors first with as_label(). write_sav() actually ignores the value labels, so the corresponding text needs to be in the factor levels.

Summary

Here are the key takeaways from this building block:

• You can seamlessly work with both SPSS and R for your labelled data
• We recommend the sjlabelled package to handle SPSS (and labelled data in general) in R.
• Labelled data can have variable and value labels (aka levels).
  • Use get_label() to inspect the variable labels.
  • Use get_labels() to inspect the value labels.
• Use as_label() to replace the numerical level IDs with the text levels.
• To assign labels to the data with dplyr-syntax use
  • var_labels(!!!variable_labels)
  • val_lables(!!!value_labels)
  • variable_labels and value_labels are (nested) named lists with column name-label pairs
• Use as.ordered() to transfer categorical data to ordinal data.
• Use as_numeric() on ordinal data to before applying quantitative statistics.
• Use haven::write_sav() to export the data as SPSS files.