Questions tagged [covid-19]

Questions either on modeling COVID-19 (e.g., epidemiology), or on including COVID-19 as a predictor in models for other variables. Questions using this tag also should have another tag (or several) to indicate the statistical content.

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How do I interpret my autocorrelation and partial autocorrelation of COVID-19 time series data?

Note: I've edited my question based on comments from @whuber. I have a time series of the USA's COVID-19 daily deaths smoothed to mitigate massive, weekly data dumps. My two-plus years of data comes ...
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2 votes
1 answer
82 views

Probability that seems to exceed 1

Suppose we have the following information based on independent events: The probability of contracting Alpha variant is .4 The Delta variant is 50% more contagious than Alpha The Omicron BA1 variant ...
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number of pairwise comparisons in Bonferroni correction

I did chi square test on data of 60 patients having COVID 19. The variable in the rows is the severity of case (mild, moderate, severe) while the variable in the columns is lymphocytes count (normal, ...
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2 answers
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Change per capita, logarithmic change or non logarithmic change?

I am currently working with Covid-19 key figures such as registered cases of infection and death. My data is a panel dataset across time and municipalities in Denmark, the set consists of several ...
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2 votes
1 answer
61 views

Calculate probablity of Covid-19 infection from 2 positive and 1 negative tests

There are two Covid-19 tests Test A: Sensitivity 92%, Specificity 99.7% Test B: Sensitivity 97%, Specificity 99.7% Assume a person takes three tests consecutively (i.e. right after another), in the ...
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How to determine the total vaccinated citizens given the number of 1st and 2nd dose administered? [closed]

Currently, there are 80,918 first COVID-19 vaccine doses and 52,949 vaccines that have been administered in my city. I am interested in looking at the total citizens who are either fully vaccinated or ...
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1 vote
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PCR vs Antigen Reliability Analysis [closed]

Disclaimer: I am not a statistician so be kind I’ve been trying to work something out. There’s been so much speculation about how reliable PCR tests are and how unreliable antigen (or lateral flow) ...
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Averaging time-dependent, heteroscedastic estimates of vaccine efficacy over time periods

Vaccine efficacy against Omicron has to be estimated for three months since the second dose. Efficacy data are given for shorter periods comprising three months. For example, the table, based on Fig ...
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2 votes
2 answers
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What specific endpoint(s) were used in determining the efficacy of the Pfizer and Moderna Covid-19 vaccines during the FDA trials?

I have been searching over various articles and pages from the CDC and elsewhere, but I haven't yet found a specific description of what endpoint(s) were used to define efficacy in the FDA Covid-19 ...
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10 votes
1 answer
647 views

How well do Covid-19 forecasts work?

I hope this question is in the scope of CrossValidated (I think so because it is in the end about statistical analyses and machine learning, I am not looking for individual opinions but for reviews or ...
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2 votes
1 answer
83 views

Help Requested - Bayes' Theorem posterior odds > 1 when applied to covid test

I took an antigen test yesterday and was trying to create a tool to help me interpret the results via Bayes' Theorem. I used actual sensitivity and specificity numbers from the CDC, calculated odds of ...
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2 votes
1 answer
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How trustworthy are biomarker estimates and conclusions in this covid vaccine paper?

My question is about the Correlates of protection against symptomatic and asymptomatic SARS-CoV-2 infection paper from the developers of the ChAdOx1/Vaxzevria vaccine. The paper establishes ...
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How to estimate Vector Autoregression during COVID-19?

Covid-19 has impacted macroeconomic forecasts. How can I avoid a vector-autoregression (VAR) model from under-estimating the forecasts? The series has undergone a massive drop from March 2020-May 2020....
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How to accommodate for covid-19 shocks in SARIMA when forecasting economic variables?

I am trying to forecast an economic variable using 1.Univariate Model 2.Multivariate Models Due to covid-19, there is a huge drop in the considered variable and it impacts the accuracy. However the ...
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SARIMA forecast of economic variables with shocks of COVID-19 [duplicate]

I am trying to fit a SARIMA model to a macroeconomic variable. However there is a huge drop in 2020-March due to Covid-19 and after 3 months the drop has been recovered. So the MAPE is very low. How ...
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3 answers
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How to combine state-level COVID-19 vaccination rates with national demographic data at the individual level?

I’m investigating possible correlations between the COVID-19 vaccination rate in the United States and the results of a long-running survey of scientific personality traits like "Agreeableness&...
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Forecasting a historically seasonal no-trend time series after COVID [duplicate]

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4 answers
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How many data points for test set in a time series

I have a monthly sales data set from 2018 January onwards. I would like to know from expert what is the optimum train test split and minimum train test split. Also to mention that my data includes ...
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0 votes
1 answer
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Why does Covid19 confirmed deaths lag behind all causes deaths?

It appears that Covid19 confirmed deaths dates lag about 10 days behind the all causes deaths. This is at least true in European countries (I didn't check this elsewhere) and is particularly obvious ...
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0 votes
1 answer
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Error models for COVID-19 prevalence data

1) Some background I'm currently learning about compartmental ODE modeling for epidemiology (inspired by the current pandemic!) and I've been exploring parameter estimation of SIR-like models using ...
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2 votes
1 answer
71 views

Appropriateness of propensity score matching when treatment is determinsitic and exogenous (e.g., COVID restrictions)?

I recently came across this paper by Sibley et al. in which propensity score matching (PSM) was applied to examine the effects of COVID-19 lockdowns on well-being and government attitudes in New ...
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1 vote
1 answer
81 views

Bayesian probability of negative COVID-19 test

Suppose if the person is infected, the test will be positive with a probability of 70%. The probability that a healthy person gets a negative test is 99.5%. The prior probability of being infected is ...
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2 votes
2 answers
130 views

How can we distinguish the effects of a lockdown from those of a vaccine?

My question is related to Covid-19 specifically, but it can be generalized to any infectious disease. I am asking this since I am reading a lot of information on several Social Media regarding one ...
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0 votes
1 answer
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What's the posterior distribution for vaccine effectiveness, given Pfizer's 12-15yo study results?

Summary: the placebo group had 1129 subjects and 18 infections. The vaccine group had 1131 subjects and 0 infections. More info here: https://www.pfizer.com/news/press-release/press-release-detail/...
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How can i use an ARIMA model to explain the an effect of news regarding COVID-19 on a stock market index?

My thoughts were to model the time series of the stock index up until the particular day for the news I am looking at and forecast using my model. Then I would compare the forecasted result to the ...
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1 vote
1 answer
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Logistic Regression: Variable total covid cases per 1MM is not significant but total covid cases (without population adjustment) is significant

I am working on a university paper regarding the effects of COVID severity (total cases per 1MM, total cases) on whether a party in an acquisition (company transaction) is more likely to be the ...
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What does it mean to have only lag significance on certain multiples of 7

I have a dataset named covid and after creating an acf graph of it , it looks something like this Why is it that it is only showing lag significance on lags which are multiples of 7 only , dose it ...
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32 votes
5 answers
3k views

How can you account for COVID-19 in your models?

How are you dealing with the coronavirus "event" in your machine learning models? Let's say you used to predict the number of sales each month. The virus affected your results last year and ...
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2 answers
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Interpreting Vaccine Efficacy

Assume I have a high school statistics class under my belt: One common misunderstanding is that 95% efficacy means that in the Pfizer clinical trial, 5% of vaccinated people got COVID. But that's not ...
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COVID-19 Shock: Time Series not Stationary Anymore

I am trying to forecast the private consumption for 2020 of a small region based on the national time series of the same variable. With some adjustments I managed to get both the series stationary by ...
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1 answer
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Fitting SIR model for COVID-19 Data UK

I want to fit a COVID-19 SIR model for UK to evaluate the lockdown measures (here: the first lockdown). My code is based on https://kingaa.github.io/clim-dis/parest/parest.html#overdispersion-a-...
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0 votes
1 answer
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Estimate recovered/infectious for SIR model

I like to fit a SIR model to COVID-19 data of UK. If i understood it correctly i need the numbers of I (infected) people (and not the reported case daily case data) which i would calculate as followed:...
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2 votes
1 answer
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How statistically relevant are COVID information about the number of infections per day?

I am French and the restrictions in place in my country are driven by several indicators, including "the total number of infections per day". For reference, it is currently given as about ...
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2 votes
1 answer
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How to group countries with similar age distributions?

How can I group the world's 200-odd countries into (say) ten groups, with each group's countries having 'similar' age distributions? I want to compare COVID-19 fatality rates across countries. But the ...
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6 votes
1 answer
247 views

Analyzing Pfizer Vaccine Efficacy: Testing a Claim about 2 Proportions

I teach Introduction to Statistics and would like to show my students how to analyze the Pfizer Phase 3 Vaccine results. Testing a claim about 2 proportions is straightforward with the Pfizer data: ...
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12 votes
1 answer
265 views

Should AstraZeneca's results be discounted?

This question is in regard to AstraZeneca's phase 3 clinical trial on the effectiveness of their COVID-19 vaccine. Patients were randomized to a two dose treatment group compared to a two dose placebo ...
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3 votes
2 answers
258 views

Baysian probability of false positive COVID-19 test

I am wondering what the probability of a false positive COVID-19 test would be in my city. I'm attempting to use Bayes Theorem to calculate this, however I'm getting very different results based on ...
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10 votes
3 answers
677 views

Why is $R_t$ (or $R_0$) and not doubling rate or time the go-to metric for measuring Covid-19 expansion?

In my head, the natural way to measure the expansion speed of an epidemic across populations of different sizes is simply fitting an exponential over recent infection numbers (with any strategy), ...
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2 votes
1 answer
51 views

Efficiency / Accuracy of Medical Tests for unknown diseases

Context : A few days ago, a few friends and I were trying to conduct a little study on the possible distribution of number of asymptomatic people infected by COVID-19 with the help of a slightly ...
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No apparent relation between two time series data

I have two time series data and I want to understand relationship between them for my a data science project that I am currently working on. The time series plots are given below : The plot of 1-...
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4 votes
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How is the reproductive number R being calculated?

The reproductive number $R(t)$ quantifies the expected number of secondary infections caused by an infected individual at time $t$. Thus, an R number below 1 will be likely to stop a disease like ...
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1 vote
2 answers
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If number of infected people grow exponentially, is R0(basic reproduction number) the coefficient in exponential function?

I am trying to learn basic reproduction number and have a very basic question. In a given time window, If number of infected people grows exponentially, for example $N_{d+1}=1.15N_{d}$ Can we say ...
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2 answers
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Effectiveness test of intervention on number of cases

Apologies if I'm phrasing this incorrectly, I want to model the effectiveness of an intervention measure on the number of patients diagnosed with a virus (COVID-19). A hypothesis test of sorts comes ...
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1 vote
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48 views

Explain the source of overfitting in choosing an additional parameter

I was going through this reddit post. It describes the 'timelapse and prediction of Wuhan coronavirus infections in Mainland China'. The guy chose to use $y=a+b*(exp(c*x)-1)$ to describe the ...
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