Title and abstract screening with OLLAMA API models using function calls via the tools argument

This function supports the conduct of title and abstract screening with OLLAMA API models in R. Specifically, it allows the user to draw on locally hosted ollama models (e.g., Llama 3 / 3.1 variants, Mixtral/Mistral, Gemma, DeepSeek and Qwen). For more information on how to install and use OLLAMA, see https://docs.ollama.com/. Be aware that this function requires that you have OLLAMA installed and running on your local machine. The function allows to run title and abstract screening across multiple prompts and with repeated questions to check for consistency across answers. All of which can be done in parallel. The function draws on the newly developed function calling which is called via the tools argument in the request body. Function calls ensure more reliable and consistent responses to ones requests. See Vembye, Christensen, Mølgaard, and Schytt. (2025) for guidance on how adequately to conduct title and abstract screening with OLLAMA models.

Usage

tabscreen_ollama(data, prompt, studyid, title, abstract, 
api_url = "http://127.0.0.1:11434/api/chat", ..., model, role = "user", 
tools = NULL, tool_choice = NULL, top_p = 1, time_info = TRUE, 
max_tries = 16, max_seconds = NULL, backoff = NULL, after = NULL, 
reps = 1, seed_par = NULL, progress = TRUE, decision_description = FALSE, 
overinclusive = TRUE, messages = TRUE, incl_cutoff_upper = NULL, 
incl_cutoff_lower = NULL, force = FALSE)

Arguments

data: Dataset containing the titles and abstracts.
prompt: Prompt(s) to be added before the title and abstract.
studyid: Unique Study ID. If missing, this is generated automatically.
title: Name of the variable containing the title information.
abstract: Name of variable containing the abstract information.
api_url: Character string with the endpoint URL for OLLAMA's API. Default is "http://127.0.0.1:11434/api/chat".
...: Further argument to pass to the request body.
model: Character string with the name of the OLLAMA model. Can take multiple OLLAMA models. Default = "llama3.2:latest". Find available models at https://ollama.com/library.
role: Character string indicate the role of the user. Default is "user".
tools: List of function definitions for tool calling. Default behavior is set based on decision_description parameter. For detailed responses, the function uses tools that include detailed description capabilities.
tool_choice: Specification for which tool to use. Default behavior is set based on decision_description parameter. For simple responses uses "inclusion_decision_simple", for detailed responses uses "inclusion_decision".
top_p: An alternative to sampling with temperature, called nucleus sampling, where the model considers the results of the tokens with top_p probability mass. So 0.1 means only the tokens comprising the top 10% probability mass are considered. We generally recommend altering this or temperature but not both. Default is 1.
time_info: Logical indicating whether the run time of each request/question should be included in the data. Default = TRUE.
max_tries, max_seconds: Cap the maximum number of attempts with max_tries or the total elapsed time from the first request with max_seconds. Default for max_tries is 16. If max_tries is not supplied, httr2::req_perform() will not retry.
backoff: A function that takes a single argument (the number of failed attempts so far) and returns the number of seconds to wait.
after: A function that takes a single argument (the response) and returns either a number of seconds to wait or NULL, which indicates that a precise wait time is not available that the backoff strategy should be used instead.
reps: Numerical value indicating the number of times the same question should be sent to OLLAMA models. This can be useful to test consistency between answers. Default is 1.
seed_par: Numerical value for a seed to ensure that proper, parallel-safe random numbers are produced.
progress: Logical indicating whether a progress line should be shown when running the title and abstract screening in parallel. Default is TRUE.
decision_description: Logical indicating whether to include detailed descriptions of decisions. Default is FALSE. When conducting large-scale screening, we generally recommend not using this feature as it will substantially increase the time of the screening.
overinclusive: Logical indicating whether uncertain decisions ("1.1") should be allowed in the default function calling setup. Default is TRUE, which means that the default function calling setup will allow for uncertain decisions. If FALSE, the default function calling setup will not allow for uncertain decisions and will only return binary decisions (i.e., "1" or "0"). This argument only affects the default function calling setup.
messages: Logical indicating whether to print messages embedded in the function. Default is TRUE.
incl_cutoff_upper: Numerical value indicating the probability threshold for which a studies should be included. Default is 0.5, which indicates that titles and abstracts that the OLLAMA model has included more than 50 percent of the times should be included.
incl_cutoff_lower: Numerical value indicating the probability threshold above which studies should be check by a human. Default is 0.4, which means that if you ask the OLLAMA model the same questions 10 times and it includes the title and abstract 4 times, we suggest that the study should be check by a human.
force: Logical argument indicating whether to force the function to use more than 10 iterations. This argument is developed to avoid the conduct of wrong and extreme sized screening. Default is FALSE.

Value

An object of class "gpt". The object is a list containing the following components:

answer_data_aggregated: dataset with the summarized, probabilistic inclusion decision for each title and abstract across multiple repeated questions (only when reps > 1).
answer_data: dataset with all individual answers.
error_data: dataset with failed requests (only included if errors occurred).
run_date: date when the screening was conducted.

Note

The answer_data_aggregated data (only present when reps > 1) contains the following mandatory variables:

studyid	`integer`	indicating the study ID of the reference.
title	`character`	indicating the title of the reference.
abstract	`character`	indicating the abstract of the reference.
promptid	`integer`	indicating the prompt ID.
prompt	`character`	indicating the prompt.
model	`character`	indicating the specific model used.
question	`character`	indicating the final question sent to OLLAMA models.
top_p	`numeric`	indicating the applied top_p.
incl_p	`numeric`	indicating the probability of inclusion calculated across multiple repeated responses on the same title and abstract.
final_decision_gpt	`character`	indicating the final decision reached by model - either 'Include', 'Exclude', or 'Check'.
final_decision_gpt_num	`integer`	indicating the final numeric decision reached by model - either 1 or 0.
longest_answer	`character`	indicating the longest response obtained across multiple repeated responses on the same title and abstract. Only included if the detailed function is used. See 'Examples' below for how to use this function.
reps	`integer`	indicating the number of times the same question has been sent to OLLAMA models.
n_mis_answers	`integer`	indicating the number of missing responses.

The answer_data data contains the following mandatory variables:

studyid	`integer`	indicating the study ID of the reference.
title	`character`	indicating the title of the reference.
abstract	`character`	indicating the abstract of the reference.
promptid	`integer`	indicating the prompt ID.
prompt	`character`	indicating the prompt.
model	`character`	indicating the specific model used.
iterations	`numeric`	indicating the number of times the same question has been sent to OLLAMA models.
question	`character`	indicating the final question sent to OLLAMA models.
top_p	`numeric`	indicating the applied top_p.
decision_gpt	`character`	indicating the raw decision - either `"1", "0", "1.1"` for inclusion, exclusion, or uncertainty, respectively.
detailed_description	`character`	indicating detailed description of the given decision made by OLLAMA models. Only included if the detailed function is used. See 'Examples' below for how to use this function.
decision_binary	`integer`	indicating the binary decision, that is 1 for inclusion and 0 for exclusion. 1.1 decision are coded equal to 1 in this case.
run_time	`numeric`	indicating the time it took to obtain a response from the server for the given request.
n	`integer`	indicating request ID.

If any requests failed to reach the server, the object contains an error data set (error_data) having the same variables as answer_data but with failed request references only.

References

Vembye, M. H., Christensen, J., Mølgaard, A. B., & Schytt, F. L. W. (2025). Generative Pretrained Transformer Models Can Function as Highly Reliable Second Screeners of Titles and Abstracts in Systematic Reviews: A Proof of Concept and Common Guidelines. Psychological Methods. https://dx.doi.org/10.1037/met0000769

Thomas, J. et al. (2024). Responsible AI in Evidence SynthEsis (RAISE): guidance and recommendations. https://osf.io/cn7x4

Wickham H (2023). httr2: Perform HTTP Requests and Process the Responses. https://httr2.r-lib.org, https://github.com/r-lib/httr2.

Examples

if (FALSE) { # \dontrun{


prompt <- "Is this study about a Functional Family Therapy (FFT) intervention?"

plan(multisession)

tabscreen_ollama(
  data = filges2015_dat[1:2,],
  prompt = prompt,
  studyid = studyid,
  title = title,
  abstract = abstract,
  model = "llama3.2:latest",
  max_tries = 2
  )
plan(sequential)

 # Get detailed descriptions of the decisions by using the
 # decision_description option.
plan(multisession)

 tabscreen_ollama(
   data = filges2015_dat[1:2,],
   prompt = prompt,
   studyid = studyid,
   title = title,
   abstract = abstract,
   model = "llama3.2:latest",
   decision_description = TRUE,
   max_tries = 2
 )
plan(sequential)
} # }