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# Generation evaluation
Now that we have a sense of how to evaluate the retrieval component of our RAG
pipeline, let's move on to the generation component. The generation component is
responsible for generating the answer to the question based on the retrieved
context. At this point, our evaluation starts to move into more subjective
territory. It's harder to come up with metrics that can accurately capture the
quality of the generated answers. However, there are some things we can do.
As with the [retrieval evaluation](retrieval.md), we can start with a simple
approach and then move on to more sophisticated methods.
## Handcrafted evaluation tests
As in the retrieval evaluation, we can start by putting together a set of
examples where we know that our generated output should or shouldn't include
certain terms. For example, if we're generating answers to questions about
which orchestrators ZenML supports, we can check that the generated answers
include terms like "Airflow" and "Kubeflow" (since we do support them) and
exclude terms like "Flyte" or "Prefect" (since we don't (yet!) support them).
These handcrafted tests should be driven by mistakes that you've already seen in
the RAG output. The negative example of "Flyte" and "Prefect" showing up in the
list of supported orchestrators, for example, shows up sometimes when you use
GPT 3.5 as the LLM.
![](/docs/book/.gitbook/assets/generation-eval-manual.png)
As another example, when you make a query asking 'what is the default
orchestrator in ZenML?' you would expect that the answer would include the word
'local', so we can make a test case to confirm that.
You can view our starter set of these tests
[here](https://github.com/zenml-io/zenml-projects/blob/main/llm-complete-guide/steps/eval_e2e.py#L28-L55).
It's better to start with something small and simple and then expand as is
needed. There's no need for complicated harnesses or frameworks at this stage.
**`bad_answers` table:**
| Question | Bad Words |
|----------|-----------|
| What orchestrators does ZenML support? | AWS Step Functions, Flyte, Prefect, Dagster |
| What is the default orchestrator in ZenML? | Flyte, AWS Step Functions |
**`bad_immediate_responses` table:**
| Question | Bad Words |
|----------|-----------|
| Does ZenML support the Flyte orchestrator out of the box? | Yes |
**`good_responses` table:**
| Question | Good Words |
|----------|------------|
| What are the supported orchestrators in ZenML? Please list as many of the supported ones as possible. | Kubeflow, Airflow |
| What is the default orchestrator in ZenML? | local |
Each type of test then catches a specific type of mistake. For example:
```python
class TestResult(BaseModel):
success: bool
question: str
keyword: str = ""
response: str
def test_content_for_bad_words(
item: dict, n_items_retrieved: int = 5
) -> TestResult:
question = item["question"]
bad_words = item["bad_words"]
response = process_input_with_retrieval(
question, n_items_retrieved=n_items_retrieved
)
for word in bad_words:
if word in response:
return TestResult(
success=False,
question=question,
keyword=word,
response=response,
)
return TestResult(success=True, question=question, response=response)
```
Here we're testing that a particular word doesn't show up in the generated
response. If we find the word, then we return a failure, otherwise we return a
success. This is a simple example, but you can imagine more complex tests that
check for the presence of multiple words, or the presence of a word in a
particular context.
We pass these custom tests into a test runner that keeps track of how many are
failing and also logs those to the console when they do:
```python
def run_tests(test_data: list, test_function: Callable) -> float:
failures = 0
total_tests = len(test_data)
for item in test_data: