The tag has no wiki summary.

learn more… | top users | synonyms

1
vote
0answers
16 views

Probability of paired combinations

There are 8 friends: Alfred, Alex, Billy, Barbara, Connie, Chris, David and Donna. The friends are paired up at random. What is the probability that at least two pairs will share the same first ...
0
votes
0answers
11 views

Combinations of products [on hold]

Let's suppose $N$ independent events. Probability of each (or k-th) event equals 1-$x_k$. I hope the following illustration will clarify what I'd like to get: Say we have five events $(N = 5)$. ...
3
votes
1answer
151 views

What's the intuition behind combinations for coin flips?

Intuitively I understand something like "10 choose 3" as someone holding out an opaque bag containing 10 different objects and asking me to put my hand in and then instructing me, "from the 10 choose ...
1
vote
1answer
34 views

Variation on the urn problem and frequency distribution

I have $6$ machines each producing different coloured balls. The balls are mixed together in a large vessel. Groups of $6$ balls are extracted at random for packing. Each pack will therefore have a ...
5
votes
2answers
59 views

Distribution of linear combination of OLS regression coefficients

I have a simple linear OLS regression $Y_i = \alpha+ \beta_1 X_{1i} + \beta_2 X_{2i} + e_i$ where $e_i \sim N(0,\sigma)$. I have estimated the regression from the data and obtained estimates for my ...
2
votes
0answers
106 views

A smarter way for evaluating combinations of samples to optimize an overall score

I have the following problem (which I simplified for clarity) that I want to find k out of n samples (here: rows) that yield the maximum score (sum of the values in ...
4
votes
0answers
48 views

Combination of letters: some repeated letters

So I was looking for an answer on this assignment we have to program but I cannot find it anywhere. I'm a computer science student, not a statistics students. (And it isn't even for a statistics ...
-1
votes
1answer
27 views

All possible Combinations of 5 variables that can take 3 values

I have five variables which can take three values as shown below V1 = {1,2,3}, V2 = {1,2,3}, V3 = {1,2,3}, V4 = {1,2,3}, and V5 = {1,2,3} Then how many rows ...
0
votes
1answer
17 views

How to combine clinical variables?

I am dealing with several clinically used variables that are not linked to each others. Those variables are correlated to worsened prognosis (some are numeral and asymmetric, therefore correlations ...
0
votes
0answers
11 views

How can I combine positive likelihood ratios?

I only have the positive and negative likelihood ratio, sensitivity and specificity for four diagnostic tests. How can I add them or combine them to obtain likelihood ratios? I do not have the ...
0
votes
0answers
6 views

How to combine diagnostic tests with only sensitivity spec, PLR and NLR

Hi ive looked at the other questions but this ones seems to be different as i only have the test results from different clinical exams in the way of sensitivity, specificity, PLR and NLR ex: facial ...
2
votes
1answer
32 views

Combination/permutations question where repetition is allowed

So I guess this is a combination/permutations question where repetition is allowed. What is the % chance that six six-sided dice will show at least 3 duplicates of the same number or that there will ...
0
votes
1answer
33 views

combining subjective probability estimates and statistical estimates for forecasting

At the end of the year forecasters usually struggle year to predict landing estimate for the financial year due to variety of reasons including volatility, unreliable demand projections, inventory ...
4
votes
1answer
48 views

Getting $k$ consecutive heads

If a coin is tossed 3 times, there are 8 possible outcomes: $$\text{HHH, HHT, HTH, HTT, THH, THT, TTH, TTT}$$ In the above experiment we see 1 sequence has 3 consecutive H, 3 sequences have at ...
2
votes
1answer
110 views

drawing balls from an urn

Suppose there are 7 golf balls in an urn and you draw balls in 3 stages without replacement. First you draw 2, then 3, and then the remaining 2. How many ways are there to do this? I believe the ...
1
vote
2answers
92 views

Sum of combination

My problem is: Evaluate: $$\sum_{i=0}^n i{n \choose i}$$ I only know that $$\sum_{i=0}^n{n \choose i} = 2^n$$ not so sure when an "i" is added. What is the step of this evaluation?
0
votes
0answers
40 views

Significance of linear combination of two insignificant regression parameters

I'm running a model with an interaction term, of the general form: $Y=b_1X_1+b_2X_2+b_3X_1X_2$, whereby $X_2$ is a dummy variable and $X_1$ is continuous. Neither $X_1$ nor $X_2$ turn out as ...
2
votes
0answers
31 views

Co-occurrence statistics for sets

I am looking for help in the following situation: I have a set of numbers $A=\{1, 2, \dots, 100\}$, and I am drawing subsets of 10 of these numbers $\{a_1, a_2, \dots, a_{10}\}$ according to an ...
3
votes
2answers
86 views

Estimating total number of people from an observed sample

The well known "German tank problem" shows how to answer the question: "If I have tanks which have an increasing serial number, and I see a sample of tanks and record their serial numbers, what is the ...
2
votes
1answer
48 views

probability of tally having a count of 0 in x variables after sampling with replacement

I am a non-statistician testing a randomising algorthm. If I have a sample of size 100 (numbered balls) with replacement and that 50 such samples are independently drawn. To my understanding, the ...
2
votes
1answer
119 views

Combining outcome measures for meta-analysis

I have to conduct a meta-analysis. Following problem occured: a single study have measured Quality of Life and therefore, used two questionnaires. Now is my question whether I have two choose one of ...
0
votes
0answers
37 views

Extract knowledge from the (possible unrelated) combination of multiple data sets

I am a beginner in this area so please bear with me. I have 2 data sets: information about the cars which were sold in particular area (cost, model, number of seats, manufacturer, etc.) information ...
0
votes
0answers
22 views

statistical distribution that would generate combination of numbers without repitition

I have set of 'n' numbers in an array. Is there a statistical distribution that would generate randomly picked 'n' numbers from the same array such that there are no duplication. For example, if I ...
1
vote
1answer
73 views

How many different ways can I arrange this committee?

A company has 20 employees, 12 males, and 8 females. Suppose we need to form a committee of 5 employees. How many ways are there to form this committee if we need 3 males and 2 females? I believe ...
1
vote
3answers
132 views

Combination of Data from Two Normal Samples not Normal?

I have two sets of data that hypothesis tests have shown to be normal and from the same distribution. I'm using MATLAB and for the way they give p-values, higher p-values suggest a better ...
0
votes
2answers
316 views

Frequency of combinations possible

I have an SPSS data set with 700+ respondents and 13 products that they could own. Each product has its own variable Product01 = 1 means they own product 1 Product02 = 0 means they dont own product 2 ...
1
vote
1answer
118 views

How to combine likelihoods from multiple binomial trials. Can we also determine the overall FDR?

A king has rounded up 1000 people suspected of counterfeiting coins, which look and feel the same as the official coin. However, only the official coin is truly fair (Pr(heads)=0.5), while all fake ...
0
votes
1answer
126 views

Probability understanding 52 C 5

Hi I have a problem undertanding this: Example: In a deck of 52 cards, 5 cards are chosen. ...
3
votes
1answer
218 views

Combine several softmax output probabilities

I would like to combine the outputs of five neural networks, each with a softmax output layer of three classes each. A typical, example output is shown below:- where Figure 1 is the output of model ...
2
votes
3answers
269 views

How to combine time-series based features with different frequencies

I have 3 features which I want to use in my classifier. They are all time-series data-based. However, they are all at different frequencies and there have different matrix dimensions. I was wondering ...
5
votes
1answer
91 views

Co-occurrence of properties in a population

I have 150 properties that may occur in a population of 10000 people. Individual people may have none, one or a couple of these properties. The properties are not mutually exclusive and have different ...
1
vote
0answers
74 views

Bayesian belief network for finding combinatory effects of multiple environmental variables on allele frequency

I'm a beginner to Bayesian belief network (BBN). I read a few articles on introduction to BBN. So I know a general idea of BBN. But I'm struggling to construct a graphical network and conditional ...
2
votes
1answer
167 views

Correlations with a linear combination means correlation with individual variables?

I was having this conversation with someone, and I feel like I have an explanation, but would greatly appreciate if someone could verify whether what I'm thinking is just completely wrong. He made ...
1
vote
0answers
97 views

Patterns in binary sequences

I have data that looks like this: 011100111110100111 111111111111110010 111100001111000011 1D lanes of streams of data. Each row signifies the presence of a ...
1
vote
1answer
329 views

How to calculate the confidence interval of a function of a combination of two linear models

We have two linear fits, one for each data-set (unfortunately they include weights but I'm willing to ignore that if there's a nice analytic solution to this). Data-set ...
1
vote
1answer
125 views

How can I get annual rates of change for combined trend estimates?

I would like to combine trend indices (gained with different methods referring to the same subject, assuming they do not differ significantly) of two different time series and to derive the combined ...
1
vote
1answer
477 views

Combining results of two classifiers to better classify a data-point

Suppose that a classifier A classifies a data-point $x$ in class LA1 with probability PA1 and class LA2 with probability PA2 (with LA1 != LA2 and PA1>PA2); and that a classifier B classifies a ...
5
votes
1answer
268 views

Probability of independent events within a specified window

So I have an event that can occur on a daily basis with probabilty 1%. There is no dependence between days. Now I can calculate the probabality of the event occuring X times in Y days: ...
0
votes
1answer
121 views

Possibilities of variables combination and conclusion

I have 11 independent variables and one intercept. If I am right, that means there are $2^{12}=4096$ possible different models, right? So does this mean, if I calculate each model and save the ...
0
votes
1answer
130 views

Trying to Calculate Basic Lunar Probabilities

I'm trying to do what I thought was a basic problem but doesn't seem to be working out properly. I'm looking at disproving a claim that tides cause earthquakes, where the main mechanism that people ...
3
votes
1answer
94 views

Validity of using the mean duration across a sample period as the trial for Student's t test or Welch's test

Business Problem We are measuring the duration of an operation on our server. We want to know if certain changes (call them treatments) make this operation faster or slower. Data Our current test ...
1
vote
0answers
269 views

Combining probabilities for sports prediction

I use two criterion ($w$ and $x$) for predicting the outcome of football matches. Analysis of historical records has provided me with two best fit linear equations. The probability that the team ...
5
votes
1answer
452 views

Understanding Fisher's combined test

I am using Fisher's combined test to fuse several different independent tests. I have a problem understanding the results in some cases. Example: Let's say I run two different tests, both with the ...
3
votes
2answers
393 views

Calculating possible combinations with restrictions

I have five additives that can be mixed into a chemical. Each one can be mixed in at a discrete percentage from 0.02% to 0.22% of the chemical (i.e. 0.02%, 0.03%, 0.04%,...0.22%). Each additive must ...
0
votes
0answers
74 views

Unique subsequences of the human genome

I am working on a project involving genomes. I am going to divide a genome into subsequences, and then do something with those subsequences. I want to know if the subsequences that I produce are going ...
2
votes
2answers
7k views

Simplify sum of combinations with same n, all possible values of k

Is there a way to simplify this equation? $$\dbinom{8}{1} + \dbinom{8}{2} + \dbinom{8}{3} + \dbinom{8}{4} + \dbinom{8}{5} + \dbinom{8}{6} + \dbinom{8}{7} + \dbinom{8}{8}$$ Or more generally, ...
4
votes
1answer
1k views

Simple combination/probability question based on string-length and possible-characters

Assuming "complete randomness" and given a string with a length of 20 characters where each character may be one of 62 possible characters: What are the total number of combinations possible? ...
7
votes
3answers
1k views

What is the probability of n people from a list of m people being in a random selection of x people from a list of y people?

If I am selecting 232 people from a pool of 363 people without replacement what is the probability of 2 of a list of 12 specific people being in that selection? This is a random draw for an ultra ...
1
vote
1answer
143 views

How many possibilities is there to choose 10 boxes of given size?

We have a collection of 40 boxes, each is one of four sizes (evenly distributed 10 of each): sizeA, sizeB, ...
2
votes
2answers
177 views

$E(\min_{1 \leq i \leq m} |x - y_i|)$

I have faced a statistical problem in a computational biology question. I will explain it in statistical language. Let's say we have the results of rolling one red die, $x$, and $m$ black dice ...