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House of Quality
So, in the last class we discussed House of Quality and then we mentioned that House of
quality is a tool which normally used in QFD, Quality Function Deployments. The
quality function deployment has multiple applications, so we will be using the house of
quality to do few things in the product development. So, first of all, we need to find out
what are the weakly satisfied customer needs in the product design process.
So, we identified a lot of customer needs and then we tried to find out the metrics
corresponding to this need. But finally, we want to know whether all the metrics are
properly identified or all of them have the same kind of influence. So, is there any weakly
satisfied customer needs that we are trying to address. Now some of the customer needs
may be very easy to address, some of them may be difficult to address.
So, what are those weakly satisfied customer needs that we need to look at based on the
metrics that we identify and then we need to look at what are the dependencies or
interrelationship between the metrics, there are some metrics when you try to change, it
may get affected, last entry, no more entries.
So, we need to find out what are the dependencies of the metrics, how each metric is
related to other metrics and what are the interrelationship between the metrics that need
to be identified and determine what product changes we can affect to improve these weak
So, the whole idea is to check what are the weak points and how do we improve the weak
points. So, that is why we are using the House of Quality and then we saw how to
develop the House of Quality. In the last class we mentioned how to do this.
So, the procedure was mentioned as you identify the customer needs its importance then
the metrics. So, what do you want to change how you will change and their relationship
between this metric and needs, how they are related? So, here we will be able to identify
how strongly they are related or how weakly they are related and then we look at the
direction which each metric needs to be improved and then we look at the benchmarking.
What is the current level of satisfaction by different products?
So, this is the benchmarking, so you will get that benchmarking of customer satisfaction
how good they are satisfied or not and then we look at the values used by the competitor
for each metric and use this one for and finally, you have a correlation matrix, which
relates the metrics and each metric how they are actually related.
This is known as the house of quality, where we try to put in all the needs metrics,
benchmarking values, and relationships. So, all that information everything is put into a
single page and that is known as the house of quality.
So, the whole purpose of adding doing this is to find out the weak needs or the needs
which are weakly satisfied, how the metrics are interrelated and finally, to decide which
metric can be changed to get the decided performance of the products. So, that is the idea
of doing the house of quality. So, this is what I discussed, I mentioned in the last class.
So, what we do is identify the customer needs. So, that is the ‘Whats’ and then determine
the relative importance, translate requirements to ‘How's’ or the metrics and use plus or
minus arrows to show the direction of improvement and then determine the relationship
of engineering design requirements to customer needs, the strength of relationship,
perform benchmarking rank them technical, rank the technical difficulty of each
requirements and finally, create the correlate the technical relationship determine the
interrelationship of the design requirements, these are the steps involved in developing
the house of quality.
So, in the lab today, you will be doing this exercise for the product that is given to you.
So, in this case, you do not that exercise of identifying the requirements or the customer
needs, you start with the customer need you assume that there are some five customer
needs you can identify directly without going through the process, can identify five
customer needs and then you need to identify all the metrics corresponding to this and
then prepare the need metric chart and finally, the House of Quality.
So, that is going to be the exercise for today and the report should be submitted
individually. So, the last two reports were group projects, group reports, but this house of
quality I want you to give an individual report in the next class.
Though this one I already explained how to get it. So, the difference is that you will be
having an arrow here, the direction of improvement, which direction you want to change,
and then you will be adding something called technical difficulty. How difficult it is to
change the metrics some metrics may be easy to change, some may be difficult to change,
so how easy to see change that will be done.
So, this is an example for the cycle fork design. So you have the needs here, you have the
metrics here and they are the relationships strongly related or weakly related you can
give. So what we will do, we will take an example and then see how to develop the
House of quality.
So, you may have first time when you do you may find some difficulty, so we will do an
exercise. I want all of you to do it in your notebook. So, the product is an iced tea
Brewer. So, might not be very familiar to you. But something called ice tea is very
common, where you put an ice cube in the hot tea and then drink that is known as iced
tea. So, this is a machine which actually delivers Iced tea when you press a button, that is
all what you have to do, you have to pay money and then press a button. You will be
getting the tea here that will be dispersed at these points.
So, now, suppose you are trying to redesign this product or are trying to design a product
better than the existing products, you need to develop a House of Quality to understand
the complete requirements and the challenges in developing these products. So, we have
to see how to develop this House of Quality. So, what is the first thing you need to know?
What is the first thing you need?
Professor: needs. So, we need to find out what are the needs of these products. Of course,
you need to go through an exercise to do this. But for the time being we assume that we
are done with that exercise and identified some of the most important needs of the tea
brewer. What are the needs you can directly tell now, as a direct need, what are the needs
for a tea brewer or a tea dispenser?
Professor: Sensor? Sensor is not a customer requirement, I mean sensor is for something
else, what for a customer asked for a sensor, it should be easy to use what you want to
say or what else?
Professor: So probably you can say good quality tea, roughly you can say quality of tea
or I mean if you want to make it very specific you can say so quality of tea, then?
Professor: Easy to assemble. So, we can actually identify many, some of them will be
very common to any product, some of them will be very specific to this product. So, like
this you can identify multiple needs from the customers and from the users. So, I will just
write down here.
So, assume that these are the customer needs we identified. Strong tea, easy to add ice,
easy to add tea, easy to clean, easy to store, brew large amounts of, contains steam these
are the, not complete you can have much more needs from here. But for the example
case, I am just assuming that these are the customer needs that you have identified and
the importance also given. So, in terms of 9 is the most important like that it comes. So,
the most important one is 9, then 5 and 3, 2 like this. Some of them are equally important.
So given the same numbers also. So, what next, we have to do?
Student: So, what you need to do is to see what are the metrics that can be used in order
to achieve this customer requirement, to satisfy this customer requirements. What are the
things that you can identify? For example, strong tea.
Student: Amount of tea powder.
Professor: Because you can have a X brand or Y brand, you cannot have such X and Y
mix rights. I mean X brand depends, does not depend on anything else. X is X only.
Anyway, will we see any other brand or any other metrics you can identify?
Professor: Thermal insulation, because so probably you had to do each one, so contain
steam, brew large amounts, what is the metric?
Professor: Yeah size yeah, size of the okay it is a given volume of this, but volume with
the product does not really ensure that it is a large amount of brew. So, the volume of
water it can contain, maybe one or you can see the volumetric efficiency. Also you can
say roughly, total volume to the volume that it can, water volume it can contain. So that
way we can actually represent that metric? So, you can identify metrics like this. So, let
me see those metrics here. So, these are the metrics that you can think of.
The temperature of water depends, I mean that actually affects the tea quality. The time
water is in contact with the tea also affects the tea quality. Volume of water in the tank
affects the large amount brew can be done or not. Temperature of exiting hot tea, that
actually affects the steam, contains steam as well as the adding ice also, the temperature
of exiting tea affects these two needs. Time needed to add tea that actually again affects
the quality of the tea.
Time to clean the products, easy to clean total volume that again affects the brew large
amounts, as well as easy to clean also, if the volume is very big or difficult to clean.
Largest size of brew, again brew large amounts. Hottest temperature again affects the
quality. Outside container I mean, hottest temperature outside the container. So, that is
the, so these are some of the metrics. I am not saying these are the only metrics that you
can use, but for this we can identify, these are the metrics that can be used.
What is the next step? So, the first step is to identify the customer requirements. That is
the first one, this is the first one and then the second one is to get the metrics. What we
will do next, we will try to prepare the chart. So, we know this is what we want to
achieve. So what we want to achieve is this one, how do we achieve it by, how do we
achieve it by playing around with these metrics. So, by changing these metrics you will
be able to meet the customer needs.
So, by changing the temperature of water or time of water in contact, you will be able to
get a strong tea. So that is the understanding, but which one to change, we do not know,
we still do not know whether all the needs are properly addressed or although all of them
are strongly related, we do not know. So, what we will do is start preparing the House of
So, we will have this strong tea, this one as the customer needs and the importance here.
So, we have needs.
Professor: So, what we are trying to do is we are actually trying to do everything
together. So, the why values actually come from benchmarking. So, we are doing
benchmarking also in this house of quality. So, what we are doing first, we will actually
prepare this part.
So, this is basically a needed metric matrix. So, we are preparing the first element that
can be considered as the needed metrics matrix that we saw. The need and metric are
shown here and their relative strength also shown. So, the dark one shows very strongly
related and the white one shows, the white circle shows that they are not strongly related
but there is a weak relationship between this metric and the corresponding needs. So, that
is the thing here.
So, what we are doing is a need and metric relationship first we identify. Of course, then
you do this, you can do it separately also and then try to bring them together. So, needs
and metrics. So, you can see now the temperature of water in the basket is directly related
to the strong tea as well as time of water is in contact is directly related, strongly related
by changing any one of this you can increase the, improve the quality of the tea.
The strong tea can be made either by increasing the temperature or by increasing the time
contact the water is in with the tea powder. So, any one of these can be used to improve
the tea quality. Similarly, easy to add ice, volume of water and the temperature of exiting
hot tea, here you can see easy to clean time to clean the product is the direct metric.
If you can reduce the time directly you can reduce the, improve the quality. But another
one is that if you increase the total volume or decrease the total volume that also may
affect the easy to clean, there is a relationship but then you need not be as strong as the
other metric time to clean is the strongest metric, the other one is the weakest, week
metric like this you will be able to see.
Similarly, this also you can have a third category as, so contains steam. So, you can have
the hottest temperature outside the container if one actually matters, this also has got a
light relationship. So, we can have three categories strong, weak, and then for the weakest
also. So, can have three categories of relationship. So, this shows how the needs and
metrics are related.
So, this each metric can be seen, we can see, each need can be connected to a
corresponding metric and one important point to be noted is that every need should have
at least one metric. So, you can see in this row, there should be at least one in each row. If
there is a blank one, that means that it does not have a metric for that. So, now we know
which are the ones strongly related which are the one weakly related.
So, all these have got only one metric, many of these have one metric. But this one has
got two metrics; they are very strongly related to two metrics. There is the first part that
we do the need and metric.
Professor: I mean there is an atmospheric temperature, when you take the tea the
atmospheric temperature is very low or very high. So, you can say I did not get the
capability to be different outside because the temperature is very high. So, cannot add,
you have to add more eyes to get the same quality. That is the, that is what actually it
says here. Yeah you are alright now.
So, that is the first step needed and metric. Now what we will do, so as he mentioned we
need to get the values. So finally, we need to get the specification saying that this is the
value I have to use for each metric. We want to know what should be the temperature of
the water in the basket, you know to get a strong tea, is it 100 degree or 99 degree or 98
degree. We don't know.
So, we need to get this value. Similarly, how long we do keep this in the, how long it
should be in contact with the tea powder we do not know. So, we need to get that value,
so at present we do not have any value. So, what we do, we will try to find out who are
the people who actually manufacture these kinds of products and what are their customer
satisfaction ratings and what are the values they use. So, we do benchmarking and we
will try to find out.
Before that, there is this direction of change also. So, we know that the temperature
increases, the tea quality increases, time increases, tea quality increases, the volume in
the water in the tank decreases, then it is easy to add ice. But the temperature of an
exceeding hot tea decreases again, making it easy to add ice. Time needed to add tea you
want to decrease, because that will actually be easy to add tea also, the time needed.
Similarly, time to clean the product you want to decrease. So, this one you want to
decrease, this one wants to increase this. So, you can actually get what is the direction
which each metric needs to be moved in order to improve the quality. So, the customer
will be more and more happy. So, by increasing the temperature you can get a much
stronger tea. Similarly, increasing the time also you will get more tea by decreasing the
time you will get more satisfaction that the time to clean will decrease.
So, this way we know what is the direction in which you want to move each metric. Now,
we will go for the benchmarking. So, the first benchmarking is the competitor
benchmarking based on the customer satisfaction. So, we assume that there are one, two,
three, four, five companies already making these products.
We will look at how these companies are performing in terms of the needs, which
companies satisfying the customer very well and for which company customers are not at
all happy. That is what we do in the competitor rating. We will see that for strong tea, so
this is the best, these two are doing very well, old fashioned way and the powdered tea
they are the best thing and the next one is the these two are not companies, but this the
Mr. Coffee iced tea maker that is the best one and this company has the lowest.
I do not remember which are the 1-2-4-5. So, this is the way we can give the rating. So
now we know who is actually best in this category. Similarly, easy to add ice, easy to
store, easy to clean everything we can actually identify the customer satisfaction. Now
what we do is, we look at the best company for this particular thing, stronger tea and then
look at what is the value they are using for these two metrics.
Because these are the two metrics affects the quality of tea and these are the two
companies which actually do, I mean this is the company which actually do the best way
to do it, we will find out what is the value he is using and we tried to find whether that,
that value we can use, that is the way how we do this.
I forgot to mention the technical difficulty also. So, technical difficulty tells how easy or
difficult it is to change the metric. Some of the metrics are very easy to change, some of
them are very difficult to change. So, this is very easy to change the volume of water in
the tank and can be easily changed by increasing the size. So, difficulty is very low. But
when the water is in contact with the tea and wants to have more time as it passes
through, then it may be a bit difficult to plan and execute. So that will be more difficult.
So, we will give you a difficult and easy also. So, one advantage is that you can decide
which one to change, the easy things can be changed or the difficult can be kept without
change also, depending on the situation. So, we have this benchmarking Competitor
benchmarking which actually gives the customer satisfaction with respect to the
customer, the products. Now we try to see what is the value they are using. So, here you
can see the value, each one what is the value they are using for each of these metrics.
For example, Mr. Coffee, what is that temperature of water in steeping baskets, we do not
know, because they consider it as a secret or they do not inform. So, question mark, we
do not know about this and this Mr. WB Coffeemaker is 98, Old Fashion is 99 powder
So, these are the temperatures that are currently known 98, 99. Similarly, each one
temporary time of water is in contact for eight seconds, not available for five seconds. So
this way, gives you an idea what is the value these companies are using and how they are
actually satisfying the customer needs.
We get all these values. Now, based on this and this information we can use and based on
what we can say, tell or what would be our target value for this or ideal value or the target
value, we can see that okay this company, Mr. Coffee Maker uses 98. So, they have a
reasonably good rating. So, either you can use the 98 itself or you can make it 99 or 98.5
to better than the, to improve the tea quality.
So, if you want to get better than this company, you can decide to have a different
temperature. Similarly, you can have a different time to improve the tea quality. So, this
way, these two by looking at the customer satisfaction of these two products and the
metrics they are using, you will be able to get a value or for your metric or for your
design, you can decide what should be the temperature of water in the tank. That is the
way how you get the target value.
So, now we write the target value here, the object target value. So, you can see it is 98 8.
So, we are assuming that okay we can maintain the same kind of quality compared to this
one, because they are well satisfied people are satisfied. So, we can actually go for 98 and
8 itself. Similarly, if the parameters can be obtained, the target values can be obtained,
something is not available, we will put it as a question one because we can do more
research and then try to find out.
So, that is the way how we actually get the target values for each and every metric. So,
we use this information and this information and depending on what the team is trying to
achieve, you will be able to get the values that are the target values for the design.
Professor: So, this one see, this technical important says that out of these metrics which
one you do more importance in the development. So, this is you are saying that okay this
is absolute values 83 percent of this change will actually affect the tea quality. So, or you
can say this is the most important one and these are the relative importance of these
metrics we say, based on these values that you can get, this again is given by the
Professor: Yeah, this is the rating and this is absolute value and based on the absolute
value given the ranking. So, 83 percent of 83 is the absolute importance of this particular
metric that is used first as an important. That is what actually and this is decided by the
designer it would not come from the, this chart. So, you need to decide which one is the
most important one and then accordingly do it. Yes.
Professor: Which one?
Professor: So, some of them are equally important. So, you had the value 45 and 45. So,
we give equal importance to that. So, we give the same ranking for that too and then we
remove one of these in between. So, 4-5-6-7 is not there. So, 7 is not given I think yeah.
So, some of them are equal. So, these two are equal, so you both have the same ranking.
It is only for the designers to know which one is, which is the one which relates to each
other metric, which metric is more important in this particular case, which metric is the
least important. So, that is what actually gives here. So, this is the most important one,
the second third and these two are equally important. The temperature of both are equally
important. That is how it is mentioned here.
Finding it difficult? Yes or no.
Professor: What is the temperature outside a container? Not true. Because if you are an
air-conditioned hall, this coffeemaker is an air conditioner hall and it doesn't really
matter. It is not that difficult to do it only outside the outdoor environment you have
difficulty in controlling, but.
Professor: No, no see suppose you are having a restaurant which is air conditioned and
you are keeping this as a machine, therefore spacing then it is very easy to control the
temperature that is what actually means. So, the last part is basically to know how these
are related to each other. Suppose I change something and the other one is going to get
affected. That is basically the interrelationship between the metrics. So, we get the top
part of the House of Quality by this.
So, what we look at here is, suppose I change the temperature of water in the basket, are
there any other metrics getting affected because of that? So, I want to increase the
temperature. Now, when I increase the temperature, is there any effect on any other
So, I look at this particular metric, the temperature of exiting hot tea. So, when it
increases the temperature of water in the basket what will happen to the tea, coming out
tea. The water, the tea coming out, it's temperature will go up, because and you increase
the temperature within the basket, of course, the tea coming out also will be having high
temperature, but what we need is basically to reduce the temperature of exiting hot tea.
So, the requirement here is to reduce, but when I increase this, this also will increase.
So, I will say there is a negative correlation between these two metrics. So, I should be
careful, if I am trying to increase this, there is something which actually gets negatively
affected. So, I should not arbitrarily change that because that may affect the other metric,
which will go against the direction of movement. That is why I will give a negative
So, you have a negative correlation here between these two metrics, this metric and this
metric has a negative correlation because, when I increase the temperature of water in the
basket the temperature of tea also goes up, which I do not want, I want to reduce the
temperature for some other reason.
So, there is a negative correlation between these two metrics. Now, look at this one
volume of water in the tank and total volume. So, this is the volume of water in the tank,
which I want to decrease. So, when I decrease the volume of water in the tank, what will
happen? The total volume also will decrease, I mean I can decrease the total volume by
reducing the volume of water in the tank, by reducing the water tank volume I can reduce
the overall volume.
So, my requirement is to reduce the overall volume and reduce the volume of water in the
tank. So, if I do one of these, this also gets affected in a positive way. So, I have a
positive co-relationship. So, now I know by changing one of these, I can actually achieve
the other also, I do not need to change both the metrics, anyone metric will actually do
this job for me. So, that is basically the positive correlation.
So, like this you can identify the relationship here negatively and that strong, very strong
and strong can be given either by a simple negative and then negative and the circle will
give how strongly they are related. Some of them will have weak relationships, some of
them will have very strong relationships. So, the weak and strong can be represented
using a circle and additional circles.
So, that is the way how you get the correlation matrix in the House of Quality. So now,
we have all this information, whatever we have discussed so far, everything is in a single
page, by just by looking at this diagram, the designer will be able to tell, which one is
easy to change which one is difficult to change and when I change something, what will
happen to the other one. So, based on this, the designer will be able to decide which are
the things he wants to change out of these metrics and then what should be the values
here I want to use for that, this is clear, it is only a question of how do we actually design
So, that is the importance of House of Quality that you can get all this information in a
single paper on a single sheet and the design decisions can be made using this and you
also know, which are the weak relationship and how the interrelationship is there, all
those things can be identified and then you can take a decision on how to go about the
design process, which one you want to change, which one you want to keep the same and
what parameters you want to use and if you use those parameters, how much satisfaction
can be obtained, all those thing can be received or understood in this diagram.
So that is the House of Quality for the products. You know why you want to make the
same, I mean so effectively what we are saying is, if you make the container big, you
have an option to increase the volume also, the volume of the water tank also can be
increased by increasing the overall volume. So, if you reduce the overall size, then there
is a possibility that overall, the water tank size also needs to be brought down.
Professor: There is no I mean, that is intentionally you do not change it, then it's but
functionally they are related. So, by changing one you can actually get the other and also
get changed. So, you want to change the size of the water tank and then what do you do?
You want to change the, one is very clear, we change the water tanks the size also will go
up, provided you have already made it as a compact one it will increase.
Now you want to increase the size of the product. Why do you want to increase the size
of the product? For some reason, then there is a possibility that you can actually increase
the size of the water also, the water tank also can increase because overall size increases.
So, there is a possibility that you can actually increase the size of the water tank also. So,
that is why they are related, whether you really do it or not is a different thing, the design
process whether you do it or not is different, but they are related to each other because
there is that possibility that you can change it, positive in the positive direction you can
Professor: So, suppose there are no products at all, see there is no product at all and you
want to design something suppose there is nobody making this tea. But it cannot be
something which was not at all existing in the world. I mean, for example, you are
making a tea brewer, there are people who make tea using conventional methods. So, you
know what is a normal temperature they use, so we will try to use those values to make
So, somewhere something will be available you will not be completely in the vacuum
when you start a design. So, you need to or you need to go and find out, suppose you are
designing a product, a new product which you want the people to carry. So, what do you
look at, you look at what other people, what things normally people carry, what is the
approximate weight of that product and what is the size of the product which someone
can hold in your hand? So, you take those dimensions as your initial target values, then
you may do a lot of iterations to find out the actual values.
Professor: This actually we need to do go through the competitors’ products, their
catalogues and the information what is available