{"id":1949,"date":"2013-07-04T11:47:49","date_gmt":"2013-07-04T04:47:49","guid":{"rendered":"http:\/\/science-technology.vn\/?p=1949"},"modified":"2013-07-04T11:47:49","modified_gmt":"2013-07-04T04:47:49","slug":"uoc-luong-du-an-2","status":"publish","type":"post","link":"https:\/\/science-technology.vn\/?p=1949","title":{"rendered":"\u01af\u1edbc l\u01b0\u1ee3ng d\u1ef1 \u00e1n"},"content":{"rendered":"

M\u1ed9t ng\u01b0\u1eddi ph\u00e1t tri\u1ec3n vi\u1ebft cho t\u00f4i: \u201cL\u00e0m sao ch\u00fang t\u00f4i \u01b0\u1edbc l\u01b0\u1ee3ng \u0111\u01b0\u1ee3c l\u1ecbch bi\u1ec3u cho d\u1ef1 \u00e1n? Ch\u00fang t\u00f4i n\u00ean d\u00f9ng k\u0129 thu\u1eadt n\u00e0o? Ng\u01b0\u1eddi qu\u1ea3n l\u00ed c\u1ee7a t\u00f4i kh\u00f4ng mu\u1ed1n ch\u00fang t\u00f4i tr\u01b0\u1ee3t l\u1ecbch bi\u1ec3u v\u00ec \u0111i\u1ec1u \u0111\u00f3 s\u1ebd l\u00e0m cho kh\u00e1ch h\u00e0ng gi\u1eadn. Xin th\u1ea7y gi\u00fap \u0111\u1ee1.\u201d<\/span><\/p>\n

 <\/p>\n

\u0110\u00e1p: R\u1ea5t kh\u00f3 \u01b0\u1edbc l\u01b0\u1ee3ng l\u1ecbch bi\u1ec3u d\u1ef1 \u00e1n (d\u1ef1 \u00e1n s\u1ebd m\u1ea5t bao l\u00e2u) v\u00ec l\u00fac b\u1eaft \u0111\u1ea7u d\u1ef1 \u00e1n ph\u1ea7n m\u1ec1m, c\u00f3 nhi\u1ec1u \u0111i\u1ec1u b\u1ea1n kh\u00f4ng bi\u1ebft v\u00e0 m\u1ecdi s\u1ef1 c\u0169ng s\u1ebd thay \u0111\u1ed5i trong qu\u00e1 tr\u00ecnh d\u1ef1 \u00e1n.<\/p>\n

Ph\u1ea7n l\u1edbn c\u00e1c d\u1ef1 \u00e1n \u0111\u1ec1u nh\u1eadn \u0111\u01b0\u1ee3c l\u1ecbch bi\u1ec3u t\u1eeb kh\u00e1ch h\u00e0ng nh\u01b0ng nhi\u1ec1u ng\u01b0\u1eddi qu\u1ea3n l\u00ed d\u1ef1 \u00e1n ch\u01b0a bao gi\u1edd h\u1ecfi l\u00e0m sao kh\u00e1ch h\u00e0ng \u01b0\u1edbc l\u01b0\u1ee3ng \u0111\u01b0\u1ee3c th\u1eddi gian cho d\u1ef1 \u00e1n (l\u1ecbch bi\u1ec3u). N\u1ebfu h\u1ecd h\u1ecfi th\u00ec h\u1ecd s\u1ebd th\u1ea5y ra r\u1eb1ng ph\u1ea7n l\u1edbn kh\u00e1ch h\u00e0ng c\u0169ng kh\u00f4ng bi\u1ebft cho n\u00ean h\u1ecd ch\u1ec9\u00a0 \u0111o\u00e1n ch\u1eebng. N\u1ebfu ph\u1ea3i m\u1ea5t s\u00e1u th\u00e1ng \u0111\u1ec3 ho\u00e0n th\u00e0nh d\u1ef1 \u00e1n nh\u01b0ng kh\u00e1ch h\u00e0ng \u0111o\u00e1n r\u1eb1ng n\u00f3 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c l\u00e0m trong ba th\u00e1ng th\u00ec t\u1ea5t nhi\u00ean d\u1ef1 \u00e1n s\u1ebd tr\u01b0\u1ee3t l\u1ecbch. C\u00e2u h\u1ecfi c\u1ee7a t\u00f4i l\u00e0 t\u1ea1i sao b\u1ea1n ch\u1ea5p nh\u1eadn m\u1ed9t ph\u1ecfng \u0111o\u00e1n? T\u1ea1i sao b\u1ea1n tu\u00e2n theo l\u1ecbch bi\u1ec3u kh\u00f4ng h\u1ee3p l\u00ed? T\u1ea1i sao b\u1ea1n \u0111\u1ed3ng \u00fd v\u1edbi c\u00e1i g\u00ec \u0111\u00f3 m\u00e0 b\u1ea1n kh\u00f4ng bi\u1ebft v\u00e0 kh\u00e1ch h\u00e0ng c\u1ee7a b\u1ea1n c\u0169ng kh\u00f4ng bi\u1ebft?<\/p>\n

C\u00f3 nhi\u1ec1u k\u0129 thu\u1eadt khoa h\u1ecdc v\u00e0 c\u00f4ng c\u1ee5 ph\u1ea7n m\u1ec1m cho \u01b0\u1edbc l\u01b0\u1ee3ng d\u1ef1 \u00e1n. C\u00f3 nhi\u1ec1u s\u00e1ch \u0111\u01b0\u1ee3c vi\u1ebft ra v\u1ec1 \u01b0\u1edbc l\u01b0\u1ee3ng d\u1ef1 \u00e1n n\u1eefa. Tuy nhi\u00ean, c\u00f3 m\u1ed9t k\u0129 thu\u1eadt \u0111\u01a1n gi\u1ea3n m\u00e0 t\u00f4i th\u01b0\u1eddng d\u00f9ng. (\u0110\u00e2y l\u00e0 c\u00e1ch kh\u00f4ng khoa h\u1ecdc v\u00e0 t\u00f4i ch\u1eafc nhi\u1ec1u ng\u01b0\u1eddi kh\u00f4ng \u0111\u1ed3ng \u00fd v\u1edbi t\u00f4i. Tuy nhi\u00ean n\u00f3 l\u00e0 th\u1ef1c h\u00e0nh). T\u00f4i khuy\u1ebfn c\u00e1o r\u1eb1ng nh\u1eefng ng\u01b0\u1eddi ph\u00e1t tri\u1ec3n n\u00ean \u01b0\u1edbc l\u01b0\u1ee3ng n\u1ed7 l\u1ef1c (d\u1ef1 \u00e1n s\u1ebd c\u1ea7n bao nhi\u00eau c\u00f4ng vi\u1ec7c) thay cho l\u1ecbch bi\u1ec3u (th\u1eddi gian).<\/p>\n

B\u1ea1n b\u1eaft \u0111\u1ea7u b\u1eb1ng vi\u1ec7c ph\u00e2n r\u00e3 c\u00e1c y\u00eau c\u1ea7u d\u1ef1 \u00e1n th\u00e0nh c\u00e1c nhi\u1ec7m v\u1ee5 nh\u1ecf h\u01a1n (c\u1ea5u tr\u00fac ph\u00e2n vi\u1ec7c) cho t\u1edbi khi b\u1ea1n nh\u1eadn \u0111\u01b0\u1ee3c nhi\u1ec7m v\u1ee5 m\u00e0 m\u1ed9t ng\u01b0\u1eddi c\u00f3 th\u1ec3 l\u00e0m trong v\u00f2ng m\u1ed9t tu\u1ea7n. (Th\u01b0\u1eddng ph\u1ea3i c\u00f3 \u00edt nh\u1ea5t 6 t\u1edbi 8 m\u1ee9c c\u1ee7a ph\u00e2n r\u00e3.) Ch\u1eb3ng h\u1ea1n, n\u1ebfu d\u1ef1 \u00e1n c\u00f3 ba ch\u1ee9c n\u0103ng. Ch\u1ee9c n\u0103ng s\u1ed1 m\u1ed9t \u0111\u01b0\u1ee3c ph\u00e2n r\u00e3 th\u00e0nh ba nhi\u1ec7m v\u1ee5; ch\u1ee9c n\u0103ng s\u1ed1 hai \u0111\u01b0\u1ee3c ph\u00e2n r\u00e3 th\u00e0nh n\u0103m nhi\u1ec7m v\u1ee5; v\u00e0 ch\u1ee9c n\u0103ng s\u1ed1 ba \u0111\u01b0\u1ee3c ph\u00e2n r\u00e3 th\u00e0nh s\u00e1u nhi\u1ec7m v\u1ee5. T\u1ed5ng c\u1ee7a t\u1ea5t c\u1ea3 c\u00e1c nhi\u1ec7m v\u1ee5 l\u00e0: 3+ 5+ 6 = 14 nhi\u1ec7m v\u1ee5. Gi\u1ea3 s\u1eed r\u1eb1ng t\u1ea5t c\u1ea3 c\u00e1c nhi\u1ec7m v\u1ee5 n\u00e0y c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n \u0111\u1ed3ng th\u1eddi v\u00e0 t\u1eebng nhi\u1ec7m v\u1ee5 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n b\u1edfi m\u1ed9t ng\u01b0\u1eddi v\u1eady th\u00ec b\u1ea1n c\u1ea7n 14 ng\u01b0\u1eddi (n\u1ed7 l\u1ef1c). Cho n\u00ean b\u1eb1ng vi\u1ec7c c\u00f3 14 ng\u01b0\u1eddi, b\u1ea1n c\u00f3 th\u1ec3 ho\u00e0n th\u00e0nh d\u1ef1 \u00e1n trong v\u00f2ng m\u1ed9t tu\u1ea7n (th\u1eddi h\u1ea1n).<\/p>\n

T\u1ea5t nhi\u00ean, \u0111\u00e2y ch\u1ec9 l\u00e0 \u01b0\u1edbc l\u01b0\u1ee3ng \u0111\u01a1n gi\u1ea3n v\u00ec th\u1eddi gian \u0111\u1ec3 ho\u00e0n th\u00e0nh nhi\u1ec7m v\u1ee5 l\u00e0 tu\u1ef3 thu\u1ed9c v\u00e0o k\u0129 n\u0103ng c\u1ee7a ng\u01b0\u1eddi th\u1ef1c hi\u1ec7n nhi\u1ec7m v\u1ee5 v\u00e0 kh\u00f4ng ph\u1ea3i m\u1ecdi nhi\u1ec7m v\u1ee5 \u0111\u1ec1u c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n c\u00f9ng l\u00fac. Tuy nhi\u00ean b\u1eb1ng vi\u1ec7c c\u00f3 \u01b0\u1edbc l\u01b0\u1ee3ng n\u1ed7 l\u1ef1c b\u1ea1n c\u00f3 c\u00e1i g\u00ec \u0111\u00f3 \u0111\u1ec3 th\u01b0\u01a1ng l\u01b0\u1ee3ng v\u1edbi kh\u00e1ch h\u00e0ng. B\u1ea1n c\u00f3 th\u1ec3 n\u00f3i r\u1eb1ng n\u1ebfu t\u00f4i c\u00f3 m\u1ed9t ng\u01b0\u1eddi, th\u00ec ph\u1ea3i m\u1ea5t 14 tu\u1ea7n, n\u1ebfu t\u00f4i c\u00f3 2 ng\u01b0\u1eddi th\u00ec c\u00f3 th\u1ec3 m\u1ea5t 7 tu\u1ea7n v\u00e2n v\u00e2n. D\u00f9ng nh\u1eefng con s\u1ed1 n\u00e0y \u0111\u1ec3 th\u01b0\u01a1ng l\u01b0\u1ee3ng v\u1ec1 n\u1ed7 l\u1ef1c \u0111\u1ec3 \u0111i t\u1edbi c\u00e1i g\u00ec \u0111\u00f3 h\u1ee3p l\u00ed.<\/p>\n

T\u00f4i th\u01b0\u1eddng th\u00eam 20% \u201cl\u00f3t ph\u1ee5\u201d v\u00e0o trong con s\u1ed1. (V\u00e2ng, \u0111\u00f3 l\u00e0 “th\u1ee7 \u0111o\u1ea1n” nh\u01b0ng n\u00f3 c\u00f3 t\u00e1c d\u1ee5ng). Cho n\u00ean thay v\u00ec y\u00eau c\u1ea7u 14 tu\u1ea7n t\u00f4i s\u1ebd y\u00eau c\u1ea7u 17 tu\u1ea7n \u0111\u1ec3 cho d\u1ef1 \u00e1n c\u00e1i g\u00ec \u0111\u00f3 \u0111\u1ec3 th\u01b0\u01a1ng l\u01b0\u1ee3ng. Nh\u1edb r\u1eb1ng n\u1ed7 l\u1ef1c v\u1ec1 c\u00f4ng vi\u1ec7c \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n l\u00e0 kh\u00f4ng \u0111\u1ed5i (gi\u1ea3 s\u1eed y\u00eau c\u1ea7u l\u00e0 kh\u00f4ng \u0111\u1ed5i) trong khi th\u1eddi gian c\u1ea7n \u0111\u1ec3 l\u00e0m c\u00f4ng vi\u1ec7c n\u00e0y l\u00e0 tu\u1ef3 thu\u1ed9c v\u00e0o k\u0129 n\u0103ng c\u1ee7a ng\u01b0\u1eddi l\u00e0m n\u00f3 cho n\u00ean ph\u1ea7n th\u00eam 20% s\u1ebd gi\u1ea3m r\u1ee7i ro v\u00e0 cho d\u1ef1 \u00e1n s\u1ef1 thu\u1eadn ti\u1ec7n n\u00e0o \u0111\u00f3 v\u00e0 \u00edt c\u0103ng th\u1eb3ng h\u01a1n. T\u00f4i hi v\u1ecdng \u0111i\u1ec1u \u0111\u00f3 c\u00f3 \u00edch.<\/p>\n

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—-English version—-<\/p>\n

 <\/p>\n

Project estimation<\/p>\n

A developer wrote to me: \u201cHow do we estimate the schedule for a project? What technique should we use? My manager does not want us to slip schedule because it will make the customer angry. Please help.\u201d<\/p>\n

 <\/p>\n

Answer: It is very difficult to estimate project schedule (how long a project will take) because at the beginning of the software project, there are many things that you do not know and things will also change during the course of the project.<\/p>\n

Most projects receive a schedule from the customer but many project managers never ask how does customer estimate the time for the project (Schedule). If they ask then they will find out that most customers also do not know so they just guess. If it takes six months to complete the project but customer guesses that it can be done in three months than of course, the project will slip schedule. My question is why do you accept a guess? Why do you follow an unreasonable schedule? Why do you agree to something that you do not know and your customer also does not know?<\/p>\n

There are many scientific techniques and software tools for project estimation. There are many books written on project estimation too. However, there is a simple technique that I often use. (This is a non-scientific and I am sure many people do not agree with me. However it is practical). I recommend that developers estimate efforts (how much work project will need) instead of schedule (time).<\/p>\n

You start by decomposing project requirements into smaller tasks (Work Breakdown Structure) until you get to task that a person can do within a week. (Usually it takes at least 6 to 8 levels of decomposition). For example, if the project have three functions. Function number one is decomposed into three tasks; function number two is decomposed into five tasks; and function number three is decomposed into six tasks. The sum of all tasks is: 3+ 5+ 6 = 14 tasks. Assume that all the tasks can be done at the same time and each task can be done by one person then you need 14 people (Efforts). So by having 14 people, you can complete the project within one week (duration).<\/p>\n

Of course, this is just a simple estimation because the time to complete the task is depending on the skills of the people who implement the task and not all tasks can be done at the same time. However by having efforts estimates you have something to negotiate with the customer. You can say that if I have one person, then it may take 14 weeks, if I have 2 person then it may take 7 weeks and so on. Using these numbers to negotiate the efforts to come up with something reasonable.<\/p>\n

I often add 20% \u201cextra padding\u201d into number. (Yes, it is a \u201ctrick\u201d but it works). So instead of asking for 14 weeks I would ask for 17 weeks to give the project something for negotiation. Remember that the efforts of work to be done do not change (Assume requirements do not change) while the time required to do the work is dependent on the skills of people doing it so having extra 20% will reduce the risk and give project some comforts and less stress. I hope it helps.<\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

M\u1ed9t ng\u01b0\u1eddi ph\u00e1t tri\u1ec3n vi\u1ebft cho t\u00f4i: \u201cL\u00e0m sao ch\u00fang t\u00f4i \u01b0\u1edbc l\u01b0\u1ee3ng \u0111\u01b0\u1ee3c l\u1ecbch bi\u1ec3u cho d\u1ef1 \u00e1n? Ch\u00fang t\u00f4i n\u00ean d\u00f9ng k\u0129 thu\u1eadt … <\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[24],"tags":[],"class_list":["post-1949","post","type-post","status-publish","format-standard","hentry","category-quan-li-du-an"],"_links":{"self":[{"href":"https:\/\/science-technology.vn\/index.php?rest_route=\/wp\/v2\/posts\/1949","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/science-technology.vn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/science-technology.vn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/science-technology.vn\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/science-technology.vn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1949"}],"version-history":[{"count":2,"href":"https:\/\/science-technology.vn\/index.php?rest_route=\/wp\/v2\/posts\/1949\/revisions"}],"predecessor-version":[{"id":1951,"href":"https:\/\/science-technology.vn\/index.php?rest_route=\/wp\/v2\/posts\/1949\/revisions\/1951"}],"wp:attachment":[{"href":"https:\/\/science-technology.vn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1949"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/science-technology.vn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1949"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/science-technology.vn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1949"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}