Questions tagged [representative]

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Correcting the results of opinion poll done on unrepresentative sample

An opinion poll should be done on a representative sample of the population, so that its outcomes give a reliable estimate of the real public opinion. Suppose I have a large database of users, who are ...
• 1,029
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How to construct homogeneous subsets table for nonparametric tests?

Does post-hoc for friedman tests or nonparametric testshave like a homogeneous subset table from SPSS? Mean doesn't represent it well so I tried using median but my data was zero-inflated so the most ...
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How to test that a sample of a discrete random variable is representative?

I am given a discrete random variable and several large samples from it. The methods how the samples are obtained are not truly random samples but are reasonable approximations to a random sample. An ...
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1 vote
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How to create representative training, validation, and test sets when working with time series data?

In my application, I am working with a relatively long time series of daily market index percentage returns (many years) and am trying to model the dependence structure of the returns from a pure time ...
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Nonrepresentative sample for causal analysis

Suppose I observe an outcome $Y_i$ for a binary policy $Z_i$ with random assignment and no spillovers such that $Y_i(1),Y_i(0) \perp Z_i$. I run the regression  y_i = \alpha + \beta z_i + \...
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How to improve sample representativeness for longitudinal data collected via an online platform?

I am working with a longitudinal dataset exploring cognitive ageing (e.g., memory performance over time). Participants complete the study annually. Inclusion criteria for this study are 1) UK resident,...
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Can I CUT a sample to become representative?

Suppose that, from a finite population, we estimated the minimum sample size as 1000 to reach our desired confidence level and error. Data was collected using an online survey and the survey remained ...
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1 vote
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Training a classifier on a highly unbalanced class distribution?

I'm trying to train a text classification model that can predict label $A$ and $B$ accurately. However, 95% of the text examples in my dataset, which is representative of the kind of data I want my ...
121 views

Creating a representative sample

I'd like to create a representative sample from a larger population for monitoring (a hold-out control). I've thought of three approaches and am trying to select between them (plus I'm open to others)...
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1 vote
29 views

How to sample for compliance when a portion of the population is already known to be non-compliant?

Say I wanted a representative sample to estimate the portion of a population that is compliant on "doing their taxes correctly". Normally, I'd do a random sample of that population to make ...
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1 vote
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How to validate representativeness of survey on new social group?

Say a new social group X emerges in society. Say you take a sample from individuals in this group X. How to validate the sample's representativeness? For samples of other parts of society, you have a ...
• 2,752
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Should folds in k-fold CV actually be representative?

I have read somewhere that the k of the k-fold CV should be picked in such a manner as to have representative validation sets (folds). This seems to me to be contradictory since the leave-one-out CV ...
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Draw a stratified sample in panel data

Question: How can we draw a stratified sample in panel data context when the stratifying variables are not fixed over time? Background: I have panel data on workers (id) over time (t). I want to draw ...
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How can you evaluate the representativeness of a sample for a given distribution?

Problem: I am looking for a metric to find the representativeness of a sample for a given distribution, being the representativeness of a random sample as the degree of capacity of the sample to ...
1 vote
51 views

Representative Observation and Random sampling

Suppose that we have a cross-sectional data set drawn by random sampling. Then, the data may represent our population of interests. We can consider two subpopulations: male group and female group. ...
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When analyzing national surveys, do I always weight the answers with the expansion factor to get represenative results?

When analyzing national surveys, do I always weigh the answers with the expansion factor to get represenative results? Alternatively, would it be wrong to just "weigh" each answer with 1 and ...
1 vote
88 views

When we up-sample the training set, don't we introduce selection bias?

When doing supervised machine learning in the health or medical domains, we often have a target class that is relatively rare (e.g., prevalence 1-10% of cases). There are a few techniques we can do to ...
23 views

Theory related to choosing high-information representative samples of a distribution

Let $X$ be a random variable of human height and suppose that $X$ is normally distributed. If our goal is to select 'representatives' of the concept 'height', a reasonable way to choose representative ...
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1 vote
55 views

How to compare sample and population characteristics?

I have a sample $S1$ of 200 people, and I obtained a subsample $S2$ of 100 people by emailing a survey link to $S1$. So, $S2$ is a nonrandom subsample drawn without replacement. In the sample $S1$, I ...
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119 views

Time dependent representation for time series events with different time gaps?

In natural language processing, we can treat characters as evenly spaced time series in RNN models where time gaps are independent of the sequence and only sequential positions matter. If I want to ...
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1 vote
32 views

Is there any appropriate technique to look for a continuous, representative part of a time series dataset?

I would like to know if there is any machine learning technique that could be used to solve the problem as follows. Imagine a time series dataset with several rows (observations) and many columns (...
1 vote
92 views

Finding the "most representative" variables of a population

Most polls use the so-called quotas method to obtain their sample. They draw candidates upon a large panel of people and add one-by-one each responding candidate to the sample unless a certain quota ...
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How to make sure that the random sample is representative for the whole sample?

I have 14k tweets and I want to code these tweets (categorize them based on their topics), but since it is difficult to do the coding for the whole dataset, I decided to take a sample from it. What I ...
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1 vote
143 views

Select a sample size form the infinite population

I have a list of every store chain in the US with at least 100 locations in the US. a) What number of those do I have to pick in order to have a representative sample of the number of locations across ...
496 views

Algorithm to get representative sample

For a dataset I wanted to pick-out some most representative points from it. Lets say the first point could be centroid, next could be the one farthest from it in the data-set(To get variance in data) &...
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1 vote
438 views

How to partition a sample into representative subsamples?

The problem is the following: take a sample $X$ of the general population $\Omega$. Each element of $\Omega$ (and hence, each element of $X$) is described by a vector of characteristics, each ...
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1 vote
111 views

How to assess geographical representativity of a sub-area? [closed]

My geographical zone $A$ is subdivided in $k$ different types of areas: $A_1 + A_2 + \dots{} + A_k = A$. These have been measured on a map with neglictible uncertainty: i.e. for any point on the map, ...
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1 vote
54 views

Representativeness of sample, distribution of age from sample compared to national sample

Please forgive my entry-level question. I have been slamming my head on the table for well over 3 hours now as I cannot seem to figure this one out. I have a sample of n=450, population is about 17m....
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Choosing data to compare collected data against

I currently have a sample of 30 data points of how long a specific process takes to complete when a particular issue occurs and am looking to compare these times to the times where it doesn't happen ...
1 vote
51 views

Can I use a stratified random sample to avoid getting a random sample that is clearly not representative?

This is a follow-up to a question of what to do if you get a sample that is clearly not representative [What if your random sample is clearly not representative? ] I have a population of 800 in 25 ...
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1k views

Evaluate Sample Representativeness of Dataset

I'm trying to check / evaluate how representative a sample is from a dataset. I'm interested in two things: Which sample best represents the original dataset Is the sample a "good enough" ...
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What is the ideal population size so that its median is a representative statistical measure? [closed]

I am perfoming a robust z-score analysis to remove trends of temporal evolution of a certain variable so that I can compare different years. It is robust because there are outliers. My data is ...
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How to check if a sample is representative of a population, across several criteria.

I have a total population of several hundred houses, which have different sizes, prices, and ages. I want to be able to select a random sample, of a few dozen or so houses, and test how ...
1 vote
62 views

Representative sample

My question is about representative samples. My population is parents of children attending public autism-specific schools. I distributed paper-based questionnaires to all the parents in the public ...
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1 vote
266 views

Raking to converting a convenience sample to representative sample

I have a convenience sample of patients in a ZIP Code Tabulation Area (ZCTA) for whom I know their gender and age. I also have census data for the ZCTA (in particular I have 1) the percentage of ...
1 vote
198 views

Relation between representativeness of a sample and sample size

Is there a relation between sample size and a representative sample? Does the sample size affect the representativeness of a sample? Context: I used cluster sampling to get a sample of the study ...
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1 vote