s**********n
发帖数: 868 | 1 I really hope some true experts could come out to clarify this issue.
I used to shift to low-gear (D3) downhill with my old Accord so that at
about 35MPH roughly no braking was needed on a particular slope I pass
everyday, and I thought that was the standard way of driving. But later I
found that it's just not applicable to many cars like my current Fusion with
only D/L2/L1 gears. Using L2 on the same slope gives you a speed of 15MPH
and 3500+rpm on the engine, which is absolutely not comfortabl... 阅读全帖 |
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b*******y
发帖数: 239 | 2 最近在看二手的SUV， 对比了很多车型， 基本想要2000年后，08年前的（因为预算的
原因）。
但是每个车型的价格和年数，里程数都有关系，作为理科生看不到有pattern的大量数
据比较烦躁，而且每次去查KBB很费时间。 于是写了个小程序按照不同Model Year和
Milage的组合来读取KBB的数据，希望能得到一些数据的pattern。
以下是一些assumption：
Model: Honda Pilot EX-L
Model Year: 2003 - 2011
Milage: 10K - 200K (完全为了数据，肯定不会去选那么高的)
Price Type: Private Trade
Condition: Good
Options: Default
数据分析：
很明显，价格按照年数增加而增加，里程数增加而减少。 希望能从数据中找出比较合
适的点，入手之后以后的贬值相对来说少点，但同时尽量靠近年数新的和里程数少的，
当然是在买到的车正常的情况下。
这个完全是一个理论数据的分析，而且也是在各种年数和里程数都在market上有的基础
上。目的是为了以后看到一款车能够大概分析理... 阅读全帖 |
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c**i
发帖数: 6973 | 3 Steven Raichlen, The Heat of India, at Home; An ancient form of cooking is
now safer and portable. New York Times, May 11, 2011
http://www.nytimes.com/2011/05/11/dining/a-tandoor-oven
-brings-indias-heat-to-the-backyard.html?scp=1&sq=tandoor&st=cse
Quote:
"A man with an Indian accent called, wondering whether Mr. Levy, a ceramic
artist, could make a large pot with a tapered mouth, no bottom and no glaze:
a tandoor.
"sparks and flames from glowing charcoal shot from its [tandoor's] mouth
"The tan... 阅读全帖 |
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b**********f
发帖数: 343 | 4 我看过一个idea，觉得不错。create一个hash table with slope of each pair of
points，如果slope相同，再用y-intercept as another level of hash. 那么在hash
table中同时拥有相同slope和y-intercept的最多的那条线就是你要找的。
这是目前我所知道的方法。抛砖引玉一下。 |
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f****g
发帖数: 313 | 5 My algorithm for this question is:
Assume there is a set of points on the plane S = {P0, P1,..., Pn-1}
maxNumOfPoint = 0
for(i = 0; i < n; i ++)
{
for( j = 0; j < n; j ++)
{
if(i == j)
{
slope Ki = 0;
}
else
{
Calculate the slope between Pi and Pj: Kj = (Yj-Yi)/Xj-Xi;
}
}
qSort(K0,...,Kn-1);
Find all the points with the same slope M;
if( M > maxNumOfPoint)
{
maxNumOfPoint = M;
|
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f****g
发帖数: 313 | 6 Hey hock,
Assume we represent a line as y = ax + b; I compute the slope between one
point pi, and all other points in the rest. Since slope and a point Pi(xi,
yi)
can determine a line, only recording the slope should work.
I might miss something? Can I give me a more specific example?
Thanks! |
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a******p
发帖数: 29 | 7 public boolean intersect(Line line2) {
return Math.abs(slope - line2.slope) > epsilon ||
Math.abs(yintercept - line2.yintercept) < epsilon;
}
第一个判断slope的也应该是"<"而不是“>"吧？ |
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S*********r
发帖数: 42 | 8 1. First group by slope, log(N)
2. Within the same slope group, check colinearity by checking whether the
line of two starts has the same slope
3. Then we can merge the colinear lines |
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t****s
发帖数: 202 | 9 最近在看房子，有个房子各方面都还好，只有一个问题.下面是工程师的检查报告和建
议的修理。大家 看看这种情况严重不严重。大概要多少钱，修完后会不会有后遗症。
多谢。地下室是finished，修得话要打开天棚，之后要补还有刷漆。
There was noticeable sloping in the floor in the kitchen and the hallway.
The sloping of the floor was caused by sagging of the fil'St floor trusses,
the header at the opening for the basement stairs, and the double trusses
that support the header. The sagging of the floor framulg has been ongoing
since the house was built and will increase in the future probably at the
same rate. Thi... 阅读全帖 |
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T****2
发帖数: 94 | 10 找builder建的新房，本来我们选的lot，看的是一大块平的草地，但是在lot最边缘有
两个铁的drainage cover,就是下水的东西。后来房子建到一半的时候我们就发现后院
成一个下
坡，坡度下到drainage cover,我们问builder， builder说要有个slope，这样水就会
淌到后院
边缘的drainer下面去了，我们说有个slope可以，但是不能这么大的坡度，有大约1-2
个feet的高度的slope。builder说加土做草坪的时候会稍微填平一点。
今天加土了之后我看到这个大坡还在，大坡和房子之间是水泥patio，大坡的终点是棵
大树，我想如果我家娃从patio跑到草地上，这么大的坡度，肯定刹不住腿，不就一头
冲到大树上去了吗。
我给builder发了个邮件，正式提了我这个concern，要求一定要加土减小坡度，估计
builer不会接受，因为之前几次提出都是口头说的，builder回答的含含糊糊的，我现
在想我们选的平整的lot，咋给砌成一个小山呢。 builder的包工头今天告诉我我们房
子的slab搞得比较高，不知道这个算不算他们的失误呢。
我想问... 阅读全帖 |
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t******l
发帖数: 10908 | 11 不过也不用老是死磕 complete a square。。。随便举一个其他的例子，比如解析几何
里，各种直线方程都是多余。。。因为万变不离其宗就是直线的 point-slope 的表述
，其本质就是 point-slope 就是 “直” 的数学语言，因为 slope 是 rise over run
。。。如果死背解析几何啥子式啥子式直线方程，那将来的三角函数一定更加死记硬背
。。。
俺有五百种不该死背公式的例子。。。可以冲五百遍没有问题。。。当然就是可能比较
费带宽。。。哈哈哈哈哈哈哈 |
|
t******l
发帖数: 10908 | 12 忍不住说几句，这个 point-slope 对应于平直空间里的 "straight"，不用相
似三角形概念证明一下，是说不过去的。。。因为这玩意儿根本不是直观到像欧几里德
/希尔伯特前几条又臭又长的公理不用说明，拿张纸直观对折就完事了。。。否则的话
，我们还要欧几里德第四第五公理干嘛？。。。勾股定理也不用那么麻烦的证明了。。
。三角形内角和也别证明啦。。。统统回到 pre-operational 算了。。。
其实我觉得基本应该是欧几里德那边从第四第五公理开始，笛卡尔那边从实数连续性完
备性公理开始，概念级不太严格的证明都得走一遍，否则严格而言属于高中数学肄业。
。。话糙理不糙。。。
：另外我觉得我们的数学概念教育确实有问题，point-slope 直线的概念是绝对不应该
当机械来讲的。。。arguably，point-slope 直线的概念，是背靠着欧几里德第四第五
公理，和勾股定理并肩，成为构筑起笛卡尔坐标系解析几何的两块最最重要的概念基石
。。。
： |
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s********e
发帖数: 135 | 13 I usually skied over 20 times per season before we got our first kid (the
situation was last for many years). After our son was born, my skiing trip
was down sized one magnitude to average twice per season. When I was ready
to take my son on the slope after he turned to 3, we had another baby. This
made my skiing plan has to be postponed for a while. Instead of skiing down
from high elevation slope and jumping around deep moguls, at the moment I
have to put the littles on the snow pad and drag t... 阅读全帖 |
|
|
T*******r
发帖数: 1246 | 15 你说的对。
为了让水自己流，就得有slope，code里有具体数字的。创造slope的一般做法是在管子
下垫土，但那样土方量太大，半天完不成，我这个属于急中生智的方法，把管子固定在
墙上来创造slope。这样就不用动土了。 |
|
G****g
发帖数: 405 | 16 generic form y=ax+b (1)
6x-3y=1 can be rewritten as y=2x-1/3. so the slope is 2.
Because the two lines are perpendicular to each other, the slopes are
negative inverse of each other. Therefore, the slope of (1) is -1/2.
Equation (1) has to be
y=-x/2+b (1)
Also, the x-intercept is -1.2, i.e. 0=(-1/2)*(-1.2)+b
b=(-1/2)*1.2.
Answer is y=-x/2)-(1/2)*1.2 or y=(-1/2)*(x+1.2). |
|
ET
发帖数: 10701 | 17 one reason i guess is the fairway slope, and green slope. just like the 3D
hole shows.. players really try to manuplate their shots too much to avoid
those slope effect..
knowledege is a double-blade sword ah..
sweating. |
|
i***t
发帖数: 177 | 18 down or up-slope?
Down-slope makes me high, up-slope makes me down. |
|
t****i
发帖数: 904 | 19 In general, I think course rating and slope is a good reflection of how
difficult it plays. Most of the time I play courses with slopes in the mid
130s including my home course, and occasionally I play courses in the 140s.
What I can tell you is that those with slopes of 140s really play very
difficult.
the |
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A*f
发帖数: 3067 | 20 too bad, i missed it.
since i was playing at canyon lake that time, even i knew ahead of time, i
still couldnt make it.
checked canyon lake and cinnbar hill, two courses got almost same rating and
slope.
cinnbar cayyon/lake: rating 71.0 and slope 132
canyon lakes: rating 71.8 and slope 133
canyon lakes conditional is slightly worse compare to cinnbar, still very
good course to enjoy. best part, there is no one else on the course from the
whole time.
also, bridges is said, a very good course, nec |
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v*****r
发帖数: 2325 | 21 2 putt on sloped green is not easy. every putt has breaks. the trick is to stay below the hole to avoid downhill 2nd putt...
find a sloped green and try it, see how many 2 putts you can make from 12
feet.
last time i tried a very sloped green at bridges, 4 putts is not uncommon.
one pole, the ball can NOT stop 8 feet around the hole, so even 10putts from 12
feet is possible....
no need to be depressed... i would take joy in reaching 500yard in two,
only very few amateur can do that... |
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v***s
发帖数: 4031 | 22 离我最近的球场Los Verdes是建在坡上，Slope是120多。个人感觉该场应该130以上，
比较难，我在那从没有打过85以下，但也很少超过90。很久没有去那打了，因为该球场
便宜，县属的，去那打的人太多，打的人技术上程度相差很大，一般要打六个小时左右
，而且，有很漂亮的海景，经常有人边打边等边拍照，也就慢了下来。
以往球打的少，换slope高的球场打球时，往往发挥不好。今年球的打比较多，年底前
，9洞18洞加起来，可以过百，所以对slope稍微高一些的130以上的场子的适应程度提
高了，也学会了，像那老版主讲的那样，要动脑子打球。一般我打不熟悉的球场，比较
保守
，而且，我开球也不是很远，大右曲基本没有，丢球次数不多。
area |
|
v***s
发帖数: 4031 | 23 离我最近的球场Los Verdes是建在坡上，Slope是120多。个人感觉该场应该130以上，
比较难，我在那从没有打过85以下，但也很少超过90。很久没有去那打了，因为该球场
便宜，县属的，去那打的人太多，打的人技术上程度相差很大，一般要打六个小时左右
，而且，有很漂亮的海景，经常有人边打边等边拍照，也就慢了下来。
以往球打的少，换slope高的球场打球时，往往发挥不好。今年球的打比较多，年底前
，9洞18洞加起来，可以过百，所以对slope稍微高一些的130以上的场子的适应程度提
高了，也学会了，像那老版主讲的那样，要动脑子打球。一般我打不熟悉的球场，比较
保守，而且，我开球也不是很远，大右曲基本没有，丢球次数不多。
area |
|
t*******t
发帖数: 1656 | 24 我常打的场子， slope <120 的基本上是 muni 级别，比较平； slope >130 的是比较
贵的场子，一般都有上下起伏。
我看到 providence 黑梯和蓝梯的 slope rating 相差很大，故有此问。
doesn' |
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c*******r
发帖数: 13580 | 25 40-55 degree is far far from a sustaining 50 degree slope. they probably
have a very long 40-45 degree slope with short sections of 55 degrees.
hitting 50 degrees is very rare in ski resorts. It's inevitable that slopes
that steep will have thin snow cover in places. Corbet's Couloir is less
than 50. Some lines at Palisades are steeper, but not for too long. |
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q*c
发帖数: 17993 | 26 【 以下文字转载自 Ski 讨论区 】
发信人: qmc (qmc), 信区: Ski
标 题: Backcountry Human Factors - six different types of danger mental shortcuts
发信站: BBS 未名空间站 (Tue Mar 4 15:02:28 2014, 美东)
http://www.powdermag.com/avalanche-education/human-factor/
Sean Zimmerman-Wall is a full-time ski patrolman at Snowbird, an avalanche
educator, and an Andean mountain guide. Check in on Tuesdays for resources
and education that will help you have a safe and good season exploring
terrain beyond the boundary line.
In Evidence of ... 阅读全帖 |
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z*********n
发帖数: 94654 | 27 那个wiki牛大了
在日本,红道是40-60度,注意是度不是百分比
Red
Intermediate slopes. At most ski areas in Japan, these constitute the
majority of the slopes (40° to 60°[citation needed], depending on how the
slopes are accounted).
黑道的区分线，100%相当于45度。 |
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n*****a
发帖数: 1327 | 28 yep. the entry was pretty steep.
I measured the slope angle; it was 42 degree from cornice to half way of
this slope. The entry should be 50 degree plus.
Check this photo taken on the same day:
The mark pole is point straight up and the hand of the rider is touching the
slope. |
|
x***k
发帖数: 3311 | 29 A long story. Three or four years ago, I went up to the Mineral Basin at
Snowbird. It was absolutely a whiteout condition but super nice powder day.
I thought the heck just go with it. I went down the steep slope and
before I knew it, I had two compete cartwheel s with head down. I had to
sit down for two minutes and get myself together. I struggled down the
slope and made back up again. I felt the dizziness – it’s like your brain
was turning but your skull was not because you absolutely... 阅读全帖 |
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q*c
发帖数: 17993 | 30 ☆─────────────────────────────────────☆
gongkege (gong) 于 (Tue Nov 30 19:59:19 2010, 美东) 提到:
各位雪人。。。
我没有滑过雪，今年圣诞节打算去滑雪，不知道改准备什么呢？
我去滑雪场，我知道滑雪板和靴子可以租。
其他东西自己买，我自己列了个表
如下：
围脖，帽子，马甲，手套，护目镜（我近视眼 戴眼镜怎么办？）
防水裤，防水外套？
这些够了吗？
哪些还需要买或者哪些是没必要买可以租的？
如果买的话，从哪里买划算，买哪些牌子呢？
我在德州，估计一年也就滑一次，
谢谢各位！
☆─────────────────────────────────────☆
TrueCabbage (...) 于 (Tue Nov 30 20:07:42 2010, 美东) 提到:
http://mitbbs.com/article/Outdoors/31239503_3.html
☆─────────────────────────────────────☆
snowrider (snowride... 阅读全帖 |
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q*c
发帖数: 17993 | 31 http://www.powdermag.com/avalanche-education/human-factor/
Sean Zimmerman-Wall is a full-time ski patrolman at Snowbird, an avalanche
educator, and an Andean mountain guide. Check in on Tuesdays for resources
and education that will help you have a safe and good season exploring
terrain beyond the boundary line.
In Evidence of Heuristic Traps in Recreational Avalanche Accidents (2002),
researcher and engineer Ian McCammon identified six different types of
mental shortcuts that were present in a ... 阅读全帖 |
|
l*******o
发帖数: 669 | 32 An avalanche prone slope typically has slope angle of 30 to 45 degree. How
can a 45 degree slope be avalanche prone if it can't hold much snow? |
|
l*******o
发帖数: 669 | 33 An avalanche prone slope typically has slope angle of 30 to 45 degree. How
can a 45 degree slope be avalanche prone if it can't hold much snow? |
|
S*A
发帖数: 7142 | 34 我还专门看了一下我的 catalogue, 没有专门针对斜坡的产品。
人家讲的就是 slope 还是要特别注意出水均匀。所以还是要head
to head overlap。其他很多注意都是为了针对 slope 的负面效
应的。我觉得 slope 其实更难做，要求要更高。 |
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z*********n
发帖数: 94654 | 35 我准备copy我邻居跟我家地形一致的，你说的slope估计和我的斜坡还不一样
我这估计不叫slope，叫hill
你那种slope估计是割草机都能上的所谓斜坡
我这是人都上不去的坡，主要就是cover住而已
比较舍得投入的邻居一般是砌墙摊平，更多人就是坡上上一些耐寒的ground cover
sprinkler做得也比较粗放。但效果很不错 |
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A*****8
发帖数: 805 | 36 前几天忙里偷闲，与一帮朋友从南到北，在从北到南徒步穿越大峡谷， 历时三天，中间露营两夜，实在是对自己体能的一个挑战。但也领略了大峡谷的壮丽，大自然的鬼斧神工。数着那几亿年时光在岩石上的沉淀，更加感受到人生的短暂，值得珍惜。
有空再多写，以及贴照片与大家分享。先看看我的一位队友写的：
The amazing torture statistics:
Day one: 10.2 miles, elevation gain 1200' (down slope not counted), average
load up hills: 28-50 lbs, slope 13.4%.
Day two:
The 4 BRAVEST SOULS : 33 miles, elevation gain: 7000'. slope in the last
three torturing miles up north rim: 15%.
3 remaining YJs: 28 miles, elevation gain: 4750'
Day three: 12.2 miles, elevation gain: ... 阅读全帖 |
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f***4
发帖数: 886 | 37 谢谢回复
那活体上直接做的（就是说不是细胞水平的），意义大吗。
看这片文献http://www.sciencemag.org/cgi/data/309/5743/2033/DC1/1
Electrophysiology. Tc1 and wild-type littermate mice, aged 4-8 months, were
anaesthetized with an intraperitoneal injection of urethane (1.8 g/kg). LTP
was investigated in the dentate gyrus using a concentric bipolar stimulating
electrode positioned in the perforant path (AP-level with Lamda, ML-3 mm
from midline, DV-1.5 mm) and a glass micropipette recording electrode
positioned in the hilus of the ipsil... 阅读全帖 |
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p****e
发帖数: 468 | 38 You can find the slopes of the two tangent lines starting from
any point on the line. If the slopes of the line is b/w these two
slopes, then the line intersect the ellipse. |
|
z******o
发帖数: 1224 | 39 。。。（2）。。。估计答案又是0.8 。。。
e.g.
a = (1,2)
b = (2,4)
regress a on b (no inct.): slope = 0.5
regress b on a (no inct.): slope = 2
a和b standardize以后，slope才都是1 |
|
w****o
发帖数: 20 | 40 Free carrier should be p forever, not n, since Na>>Nd.
If I understand correctly, you mean, Na=1e15 (i.e., 1x10^15/cm^3),
Nd=0.5e14=5e13,
log[p] Vs. 1/T:
linearly decrease (slope=Eg/2k) to Na-Nd at a small 1/T (how small? need to
know Si density of states), then a little plateu, then decrease at a slope of
(Ea-Ev)/k to Nd, then decrease at a slope of (Ea-Ev)/2k.
It's not a shallow dopant, but can be ionized at some high temperature.
Intrinsic thermal excitation (with effective activation energy |
|
s*****c
发帖数: 753 | 41
Because in this coordinate, the ball didn't travel just h in vertical
direction. Assume the time it takes is t, it travels V0*t in the slope
direction.
Assume the slope have angle of theta with horizontal direction. The
acceleration of the block (ball) along the slope is g*sin(theta).
The time it takes for the block (ball) to accelerate from V1 to V2 is
t=(V2-V1)/(g*sin(theta)).
The EXTRA distance that the block(ball) travels is V0*t.
The EXTRA vertical distance the block travels is V0*t*sin(th |
|
s********l
发帖数: 1195 | 42 问题是现在想给出一个合理的slope和slope的error
他想在report这个slope error的时候也能反映实验数据的accuracy
我都想
把每个点的error bar在图上触及范围连起来描出来做个区域
然后找这个区域里能达到的最大和最小斜率，加上fitting error，作为最后report的
uncertainty
有人觉得这个方法有一丝道理么？ |
|
s*r
发帖数: 2757 | 43 in theory you can do multi-level hierarchical model, you may assume the
slopes of all these small segments are from a (normal) distribution of
slope, all intercepts are from a distribution of slope |
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l****u
发帖数: 529 | 44 No, there will not be such misleading conclusions. After fitting the
model, you go to
check the slope. If there are nonzero slopes, you make a contrast to
demonstrate unequal slope. If the interaction exists, the p-value of the
contrast must be significant.
and A |
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f******y
发帖数: 2971 | 45 suppose two random variables, X and Y, mean of them are very small.
I can get the slope by linear regression lm(Y~X);
I can also do PCA,
data = data.frame(X=X, Y=Y);
princomp(data);
I expected the slope of the first PC vector to be very close to the slope
given by linear regression. I tried it in R, the results are very different.
Anyone can explain? |
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J*****n
发帖数: 4859 | 46 It makes me confused.
I have two series, x and y.
When I run y = ax + b, I got:
Call:
lm(formula = y ~ x)
Residuals:
Min 1Q Median 3Q Max
-38161 -5115 -19 4550 40688
Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) 1.300e+03 1.221e+03 1.065 0.29
x 1.058e+00 4.398e-02 24.057 <2e-16 ***
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
Residual standard error: 11210 on 84 degrees of freedom
Multiple R... 阅读全帖 |
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c********h
发帖数: 330 | 47 我从来没看过mixed model的R2
但是我觉得你的null model里，去掉了fixed effect，但还保留的random effect的
slope，这个不是很make sense呀
我觉得至少要有fixed effect的slope才有random slope存在的意义 |
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a*****i
发帖数: 1045 | 48 一个Mixed model的模型。两组人类，一组有病的，一组没有病，5个时间点，主要比较
他们的mmse score 随时间的变化，covariate 有年龄和housing conditions(3个不同
的housing conditions) 这这个model里面，我们用了random intercepts and random
slopes.
1. 在开始时间段，发现两组人类，两组的mmse score的variance 一组大，一组很
小，问问 mixed model 怎么take this into count, 还有两组observations,一组明显
很多人，一组很少人。想问问mixed model count for random effects, 那么人在这里
就是random effects, mixed model 是相当于两个个组分开做linear regression的，
所以并无所谓两组人，一组的variance很大，一组的variance很小。还有两组人数不一
样的问题，unbalance data都可以解决了吗？
2. 我们做了一个cor... 阅读全帖 |
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z**********e
发帖数: 22064 | 49 http://www.peruviantimes.com/06/beyond-machu-picchu-choquequira
Beyond Machu Picchu -- Choquequirao, Lost City in the Clouds
By Gary Ziegler --
The first rays of morning sunlight illuminate the great stone altar,
streaming through a square opening over my head. “Inti camac sumac,”
chants the priest. Soaked in sweat, I fight the bindings holding me to the
stone as the grinning, looming, scarlet-cloaked figure slowly brings down a
gleaming, bloodstained bronze knife toward my heaving chest.
“Jefe,... 阅读全帖 |
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