Ethnomethodology, a sociological approach pioneered by Harold Garfinkel, focuses on how people make sense of their everyday lives and interactions, and the methods they use to create and maintain a sense of social order. When considering whether it helps in getting reliable and valid data, it's important to define these terms within the context of qualitative research.

Reliability refers to the consistency of a measure, meaning that if the research were repeated under the same conditions, it would yield similar results. In ethnomethodology, achieving traditional reliability is often challenging. Its focus on unique, context-dependent interactions, the researcher's deep immersion, and the interpretive nature of the analysis means that exact replication is difficult, if not impossible. The 'data' are not easily quantifiable or standardized, making inter-rater reliability or test-retest reliability problematic. However, ethnomethodologists might argue for a different kind of reliability, such as the consistency of the researcher's interpretive framework or the coherence of the findings within the specific context studied.

Validity refers to the accuracy of a measure, or whether it truly measures what it intends to measure. Ethnomethodology excels in certain aspects of validity:

1. Ecological Validity (or Face Validity): Ethnomethodology studies social phenomena in their natural settings, capturing the lived experience and the 'members' methods' of making sense of the world. This provides a high degree of ecological validity, as it accurately reflects how people actually behave and interact in real-life situations, rather than in artificial laboratory settings.
2. Interpretive Validity: It provides deep, rich insights into the subjective meanings and understandings that individuals bring to their interactions. By focusing on the 'how' of social order, it offers a valid understanding of the processes of meaning-making.

However, ethnomethodology often faces limitations in terms of external validity (generalizability). Because its studies are typically micro-level, context-specific, and deeply qualitative, generalizing findings to broader populations or different social contexts is not its primary goal and is often difficult.

In conclusion, ethnomethodology provides highly valid data in terms of capturing the authentic, lived experience and the interpretive processes of social actors within specific contexts. It offers profound insights into the construction of social reality. However, its unique methodology and focus on context-specific meaning-making make it difficult to achieve traditional notions of reliability and generalizability as understood in quantitative research. It offers a different, yet crucial, kind of 'data' – one that prioritizes deep understanding over broad statistical representation.