These two documents are definitely necessary and are independent of one another. The DID is needed to create the DSD. Each design input should have a concrete metric, design specification, it should adhere to. The inputs would be recorded in the DID and the metrics should be in the DSD.
There are several advantages to having separate documentation. For one, a separate DID allows for more general specifications (e.g. survive environmental conditions, perform as well as or better than a predicate device) without having to quantify these values at the creation of the product. Since most products are created cross-functionally or as a team, a separate DID now lets the team define what the product will do/look like without getting into the details. This lays a foreground for more research and testing, saving time in defining the device and getting approval from upper management. Having a separate DSD now let's you continuously update these metrics as more research and testing is conducted. It wouldn't be necessary to get approval from management after each update, and each department can fill in their blanks as they progress but obviously this document should be sent for review during major milestones. This step will be much longer than preparing the DID.
Design input document: The purpose is to give the reader a broad general understanding of the system or component. There may be many levels of design documents. It contains the physical and performance requirements of a device that are used as basis for device design. It appropriately addresses needs of user and patient. The purpose is to give the reader a broad general understanding of the device and its components. Design specification document describes the details of either all or specific parts of a design. Establish the product features and its processes, including process handling, sample processing, throughput, reliability, temperature and humidity, power, fluid ingress, sound and calibration.
Based on the Indication for Use, the input documents describe Requirements which will achieve that indication, expanded into Usability, System and Technical Requirements. Design specification will elaborate further details of specifications.
Each document serves a different purpose. The DID gives a broader view of the product, outlining certain indicators and/or how it will function in a general sense. This document is mainly targeted towards people who are just trying to understand what your product is. However, the DSD gives the specifications of each part of the product. This section is more technical and will be looked at by people who actually understand these technicalities.
The purpose of the design input document is to define each user need as an objective and measurable design input. While developing the product each of these inputs must be addressed and included in the design specification document. This document should have all of the necessary details required such that another company can pick up the document and create the same product.
There should be no ambiguity in any dimensions or functions listed in the document. The design input document should be completed early on and will have little to no changes. In contrast, the design specification document will often have a number of TBD's that will be filled in as the product is developed and tested. The two documents serve different purposes.
A design specification document (DSD)is a detailed document which provides information about a designed product or process. For example, the design specification must include all necessary drawings, dimensions, environmental factors, ergonomic factors, aesthetic factors, maintenance that will be needed, etc. It may also give specific examples of how the design should be executed, helping others work properly. Advantages include, DSD gives a proper idea about how the product become. Disadvantage includes, high detailed specification is provided which is sometimes not required. A design input document (DID) gives the basic desire for the product. It is a broad type of document. Whole team of the organization gives the input also the customers gives the input. Market and customer desires are taken into account. The design input requirement is documented and reviewed and approved by a designated individual. Advantage includes DID are build upon the user needs and intended use. It makes sure that design input is clear and objective. Disadvantage includes, it does not provide specific description so designing the product becomes difficult.
Each of the documents explains the other's disadvantage. Not being specific enough can have it's drawbacks, as well as being too specific. The advantage of the DID is that you can show a customer a broad view of what the product will look like, and at the same time they can have a say in coloring etc. The DSD allows more technically inclined individuals to see exactly what is going on and see if the design is feasible.
The advantages of having each document is that it gives the team time to plan out their design study and to get a general idea of what they need their product to be. With the DID the team is able to first submit a document in the earlier stages of the process where it gives them a general idea of what items and specs they need for their model. The DID also helps set up the later stages when you need to create the DSD. A disadvantage is that although it helps with the general needs of the client, it does not list anything specific that needs to be done, which will require more work and meetings later on to confirm what is needed, and it can give too broad of a description to the device where some specs will need more elaborating. The advantage of the DSD is that it maps out exactly what is needed from the product, providing clear details and instructions for the design team and manufacturing team to work off of. The disadvantage is that when testing for the verification and validation process, the specs may be too specific and can hinder your design process. The disadvantage with the DSD is that it requires more time to make it perfect, so that you will not have to take more time making change request to the document later on. It may also be the reason why your design is failing and will not pass because of how specific the details were and because of not anticipating these details interfering.
I do not necessarily think that there are advantages versus disadvantages to these two documents as they both offer very crucial yet distinct purposes. The Design Input Document serves to provide the basic customer needs while the Design Specification Document includes the specifics of the device. However, there must be a DID for there to be a DSD. Additionally they are needed for validation and verification in Design Control.
When completing design verification, the DID is used to verify that the device meets the requirements set by the customer. Verification ensures that all the customer needs are addressed through checking if the inputs have an output. If the device fails verification, then the DSD must be reviewed, investigating the specifics of the device. Once the verification and validation report is completed, the results are documented in the DSD. Verifying and validating a medical device necessitates the need for these two documents, providing information for the development of the device.
sin3, I think you switched verification and validation a little in your mind. Verification determines, like you said, every input has an output. Those inputs would come from the DID. Validation however, is what is used to determine whether or not the product fits the customer needs, not verification. Other than that, I agree with the rest of your points.
I believe the advantage of separating the two documents is that it helps break down the project and makes it easier to conceptualize. Since the DID is the first document following the PDF and DDP that goes more into listing the parts or components that will compose the product, it is beneficial to get a vague idea first. This will allow the project team to better comprehend the features of the product in relation to the needs of the customer without having to worry about the exact specifications or components. As an example, I feel the DID is like drawing up a rough sketch of your design for a poster on a piece of paper with a pencil. In this rough draft, the exact placement of all the text or pictures is not specified, but rather allows you to get a better picture in your mind of what you may want to do. Therefore, once the team has a better understanding of the project by composing the DID, they can then begin to research and brainstorm the exact placement, dimensions, components, etc. that will compose the development of the product for the DSD. Overall, I believe the separation of the documents provides the advantage of being able to gain a better understanding of what the project team will like to do in terms of developing the product.
The DID contains the desired inputs of the product. These inputs are more general, but provides all departments a rough idea of what needs to be achieved. The marketing department plays a major role in the DID since it researches other products that perform a similar function, in order to include inputs that will make the proposed product better (and stand out) from the rest. Marketing also considers the demands of potential clients and other departments when completing the DID. The DSD, on the other hand, includes more specific parameters with ranges/tolerance that the product must stay within. The DSD can include sketches/blueprints and prototypes that were created from the DID. Both of these documents are important since they allow everyone on the team to visualize what the final product should include. The inputs on both of these documents are also necessary for verification and validation testing. These tests are required to ensure that the quality and safety of the product is not compromised.
Definitely in agreement with much of what has been said.
Two ideas put forward so far best capture the contrast between the DID and DSD.
The idea that they are each for different audience, and the idea that the DID represent a high level design while the DSD represent a low level design.
From this I would further simplify the distinction by offer the following.
The DID can be thought as denoting "What" is desired.
The DSD can be thought as denoting the "How" of the design.
A consumer is usually concerned with what.
While the producer needs to concern with how.
Consider a mobile phone. Most consumers have a very high level understanding of what the does:
makes phone calls, permits internet access, etc. But already even just those two high level description could spawn hundred of low level requirements detail how such service shall be realized.
What are the pro and cons?
A con of the DID is that it lacks specificity. It is more vulnerable missing customer real desire.
A con of the DSD is it further away from the customer visibility. It is more vulnerable to having less feedback to affirm its assertions. This the reason for the Design Matrix to try to constrain the DSD via forcing a correspondence with the DID.
I believe both the documents are important as the product needs proper binding and specifications are needed in order for the product not to fail under any circumstances. DID is the initial document that specifies how and what the product requires whereas after that what the process actually needs for it o function the way it should DSD is required.
In my opinion, to say that the Design Input Document (DID) and Design Specification Document (DSD) both have disadvantages is the wrong way to describe them, since each intentionally created for a different purpose. The DID is built around the customers or the market's desires and interests. It is an important first step, because without market interest, the best-made product in the world is useless. The DSD is where most of us as scientists come into the picture. The DSD document is about details and precision to ensure that a reliable product is created. A more accurate assessment would be that the DID and DSD are co-dependent; working in tandem they build something greater, and if a manufacturer conducts this process in the optimal way, it can result in a continuous quality loop that starts when a product is launched but is sustained through subsequent product upgrades and revisions.
In design controls, there is the DID and DSD documents. DID is design input and gives a broad description of the product (ex, "red knob"), whereas the DSD is design specification and gives a very specific description(ex, "red knob 3cm in diameter dyed with red #5 from Vendor x with a tolerance of 0.001cm"). What do you think the advantages and disadvantages are of each document and why are they both necessary?
Both the DID and the DSD work hand in hand with each other. Without the DID you can not get the DSD of the Device.
I like to look at this from the quality and production standpoint of any company. Before any product is approved to begin production, Project Managers and Product development gets all the input they need from the customer and also, Sales and Marketing put in what the market size will be and the sales outcome.
After the input has been gathered and documented, all the Input gathered are then narrowed down into a Spec, giving every specification of the input and rationale, this is put into a well documented form which production will have to follow every step strictly. The spec gives comprehensive detail as to what is needed down to how quality checks are going to be done during production and how many samples of this will have to be taken and sent out for testing and evaluation before it is shipped.
The advantage of the DID is that it tells you exactly the type of component needed for that device without giving details. This gives a larger room as to different vendors that can supply this component for the device. The disadvantage of this is that you do not know the right spec that will work with that device the way it should and knowing that different vendors will have the same red knob but with different specs. This is where the DSD advantage comes in, giving a detailed description as exactly what kind of red knob to go for and how best it will work with the device. The only disadvantage is when the output does not work as intended, you have to go back to the spec and look for what steps would have caused the problem and then you have to make a change to the spec which will require another document to be filled out called the design change control.
But in all the DID will depend on the DSD to give a well detailed description of what is needed that will be compatible with the Device while the DSD looks to the DID to what kind of spec best fits the input given. So both the DID and DSD are important in design control.
