Why is it important to know the difference between subjective and objective data in nursing? Both types of data are essential pieces of the clinical story, each with different strengths. However, it is important to differentiate the types of data not only for charting purposes, but also to communicate with others on the care team.
What is Subjective Data?
Simply, subjective data can be influenced by a person’s experience, opinions, or preferences. This type of data is often described qualitatively (nonnumerical). This type of data is open to interpretation and may change depending on who is describing the data. However, these qualities do not make it less valuable. On the contrary, subjective data often adds important detail and context to objective data.
What is Objective Data?
Objective data is not open for interpretation. It does not matter who is measuring or collecting the data, they should get the same result. Objective data are often numerical, although it does not always have to be. Overall objective data do not change depending on who the observer is or what context it is collected in.
Subjective vs. Objective Data in Nursing
Nurses constantly observe, measure, and document using subjective and objective data. Another way objective and subjective data are described in the nursing context is by “signs” versus “symptoms.”1 Signs are the data that the nurse collects during an assessment, including vital signs, visual inspection, auscultation, lab work, etc. Signs are the data that the nurse can objectively confirm, and another nurse with the same skill and training would likely come to the same result. While there is some subjectivity in assessment (describing pitting edema as 2+ versus 3+), overall, there should be agreement between similarly trained nurses.
In contrast, symptoms are what the patient tells us they are experiencing. Although not less valuable to clinical evaluation, there is often no way to objectively confirm symptoms. A detailed patient history is a key part of a thorough assessment. However, most of these data will be subjective.
As a starting example, a patient may tell their nurse that they are feeling nauseous. This is a subjective experience because the nurse cannot confirm that the patient is nauseous. They only interpret what the patient tells them. However, the nurse can objectively say that the patient’s skin is clammy, that they are tachycardic and that they vomited 300 ml of green emesis.
Nurses may use subjective and objective data to create a nursing diagnosis and plan care for their patients. However, in charting and communicating with colleagues, it is best to use both subjective and objective data to tell a clinical story. To reduce bias in evaluation and communication, subjective data should be described in detail.
Examples of Subjective and Objective Data in Nursing
One setting that relies heavily on subjective data is psychiatric nursing. Much of the assessment uses what the patient tells the nurse about what they are thinking and feeling. However, these data can also be supplemented with objective data. For example, the patient may tell the nurse that they feel depressed (subjective). This is important information, but the nurse could supplement these subjective data with the objective data that the patient speaks in a slow, monotone voice and does not make eye contact with the nurse. They may also share with the care team that the patient has not eaten and has not been out of bed in the last few days. So instead of simply charting the patient “is depressed,” the nurse could describe this objective data that are far more informative to others on the care team.
Another example of a subjective assessment is that the patient is “short of breath.” This is frequently used to describe the sensations of patients when they have difficulty breathing. But what does this actually mean? Saying that a patient is short of breath could range from being slightly tired of walking up the stairs to barely being able to protect their airway. Therefore, while “short of breath” can be used as a descriptor in an assessment, it should be supported by objective data. Objective data that might increase the specificity of “shortness of breath” could include respiratory rate, pulse oximeter reading, lung sounds, blood gasses, and the color of the patient’s skin are objective data that could be used to support stating that the patient is “short of breath.”
Reliability
Another way to describe the reliability of the data is to ask how trustworthy your data is. For example, when describing numerical data such as a blood pressure reading or laboratory value, if the data are reliable, you will get the same result if the test is repeated. An example in which an objective measure must be interpreted with caution is COVID-19 antigen testing. A negative antigen test is an example of quantitative data (no room for personal interpretation). However, at home tests range between 69%-83% sensitivity2 (the ability of a test to identify patients with a disease correctly).3 Knowing this, the nurse must use clinical judgment to decide how trustworthy the test is. This could include cross-validation with symptoms, patient history, or other assessments. This also shows that just because data is objective, it is not always reliable.
The reliability of subjective data is more difficult to assess. Since subjective data are related to a person’s experience, it can often not be confirmed or denied. There are some questions a nurse can think about to determine reliability of subjective data. For instance, is the information coming from the primary source, the patient themselves or is a family member communicating on their behalf? Is there any reason (dementia, very young children) to believe the patient may not be cognitively able to describe their experience?
Generally, subjective data are not used alone to make clinical decisions but should be corroborated with objective data.
Clinical decision-making requires gathering data from multiple sources to understand the clinical situation. Therefore, nurses must make clinical correlations between objective and subjective data to ensure best practice.
Subjective and objective data: Which is more important?
Now that we have defined the difference between objective and subjective data, you may ask which is more important to nursing practice. While the biomedical model often prioritizes objective data, subjective data provide insight into the patient’s experience. Therefore, nurses must integrate objective and subjective data into one coherent clinical picture. Overall, subjective data are helpful in gaining context and details of the clinical story, while objective data add specificity and certainty. In nursing practice, both subjective and objective data are useful and should be used together.
References
- St-Amant O, Hughes M, Morrell S, Mistry S. The Complete Subjective Health Assessment.
- Chu VT, Schwartz NG, Donnelly MAP, et al. Comparison of Home Antigen Testing With RT-PCR and Viral Culture During the Course of SARS-CoV-2 Infection. JAMA Intern Med. 2022;182(7):701. doi:10.1001/jamainternmed.2022.1827
- Sensitivity, Specificity, Positive and Negative Predictive Values | MarinStatsLectures. Accessed December 19, 2022. https://www.youtube.com/watch?v=eeM7KPRNlSs
