Posts by Tags

1-way ANOVA

Power calculations for 1-way ANOVA with possibly unequal group sizes

Published:

I was recently asked to do sample size and power calculations in the setting of a 1-way ANOVA with unequal group sizes. There are solutions to do this when the group sizes are equal, but the answer is not as commonly available for the case where group sizes are unequal.

2x2 factorial design

AUC

AUC and AUPRC for non-informative or “no-skill” risk score

Published:

Doing some math to show that the area under the receiver-operating characteristic curve (AUROC or AUC) for a non-informative or “no-skill” risk score or classifier (e.g., coin flip) is 0.5, and the area under the precision-recall curve (AUPRC) is the outcome prevalence.

AUPRC

AUC and AUPRC for non-informative or “no-skill” risk score

Published:

Doing some math to show that the area under the receiver-operating characteristic curve (AUROC or AUC) for a non-informative or “no-skill” risk score or classifier (e.g., coin flip) is 0.5, and the area under the precision-recall curve (AUPRC) is the outcome prevalence.

AUROC

AUC and AUPRC for non-informative or “no-skill” risk score

Published:

Doing some math to show that the area under the receiver-operating characteristic curve (AUROC or AUC) for a non-informative or “no-skill” risk score or classifier (e.g., coin flip) is 0.5, and the area under the precision-recall curve (AUPRC) is the outcome prevalence.

PAF

Power calculations for population attributable fraction (PAF)

Published:

A collaborator recently asked me to do power calculations for the population attributable fraction (PAF) of a dichotomous exposure, $F$, for an incident outcome, $D$. In a previous iteration, we had focused instead on using standard sample size and power calcuation approaches to get a minimum detectable relative risk (RR) assuming known sample size, outcome rate, exposure prevalence, and 80% power. While there is a paper by Browner and Newman (1989) for sample size and power for the PAF, I think an alternate approach could use the minimum detectable RR that I had already computed and the relationship between the PAF and RR.

RR

Power calculations for population attributable fraction (PAF)

Published:

A collaborator recently asked me to do power calculations for the population attributable fraction (PAF) of a dichotomous exposure, $F$, for an incident outcome, $D$. In a previous iteration, we had focused instead on using standard sample size and power calcuation approaches to get a minimum detectable relative risk (RR) assuming known sample size, outcome rate, exposure prevalence, and 80% power. While there is a paper by Browner and Newman (1989) for sample size and power for the PAF, I think an alternate approach could use the minimum detectable RR that I had already computed and the relationship between the PAF and RR.

Unequal group sizes

Power calculations for 1-way ANOVA with possibly unequal group sizes

Published:

I was recently asked to do sample size and power calculations in the setting of a 1-way ANOVA with unequal group sizes. There are solutions to do this when the group sizes are equal, but the answer is not as commonly available for the case where group sizes are unequal.

minimum detectable PAF

Power calculations for population attributable fraction (PAF)

Published:

A collaborator recently asked me to do power calculations for the population attributable fraction (PAF) of a dichotomous exposure, $F$, for an incident outcome, $D$. In a previous iteration, we had focused instead on using standard sample size and power calcuation approaches to get a minimum detectable relative risk (RR) assuming known sample size, outcome rate, exposure prevalence, and 80% power. While there is a paper by Browner and Newman (1989) for sample size and power for the PAF, I think an alternate approach could use the minimum detectable RR that I had already computed and the relationship between the PAF and RR.

no skill

AUC and AUPRC for non-informative or “no-skill” risk score

Published:

Doing some math to show that the area under the receiver-operating characteristic curve (AUROC or AUC) for a non-informative or “no-skill” risk score or classifier (e.g., coin flip) is 0.5, and the area under the precision-recall curve (AUPRC) is the outcome prevalence.

non-informative

AUC and AUPRC for non-informative or “no-skill” risk score

Published:

Doing some math to show that the area under the receiver-operating characteristic curve (AUROC or AUC) for a non-informative or “no-skill” risk score or classifier (e.g., coin flip) is 0.5, and the area under the precision-recall curve (AUPRC) is the outcome prevalence.

population attributable fraction

Power calculations for population attributable fraction (PAF)

Published:

A collaborator recently asked me to do power calculations for the population attributable fraction (PAF) of a dichotomous exposure, $F$, for an incident outcome, $D$. In a previous iteration, we had focused instead on using standard sample size and power calcuation approaches to get a minimum detectable relative risk (RR) assuming known sample size, outcome rate, exposure prevalence, and 80% power. While there is a paper by Browner and Newman (1989) for sample size and power for the PAF, I think an alternate approach could use the minimum detectable RR that I had already computed and the relationship between the PAF and RR.

power calculations

Power calculations for 1-way ANOVA with possibly unequal group sizes

Published:

I was recently asked to do sample size and power calculations in the setting of a 1-way ANOVA with unequal group sizes. There are solutions to do this when the group sizes are equal, but the answer is not as commonly available for the case where group sizes are unequal.

Power calculations for population attributable fraction (PAF)

Published:

A collaborator recently asked me to do power calculations for the population attributable fraction (PAF) of a dichotomous exposure, $F$, for an incident outcome, $D$. In a previous iteration, we had focused instead on using standard sample size and power calcuation approaches to get a minimum detectable relative risk (RR) assuming known sample size, outcome rate, exposure prevalence, and 80% power. While there is a paper by Browner and Newman (1989) for sample size and power for the PAF, I think an alternate approach could use the minimum detectable RR that I had already computed and the relationship between the PAF and RR.

relative risk

Power calculations for population attributable fraction (PAF)

Published:

A collaborator recently asked me to do power calculations for the population attributable fraction (PAF) of a dichotomous exposure, $F$, for an incident outcome, $D$. In a previous iteration, we had focused instead on using standard sample size and power calcuation approaches to get a minimum detectable relative risk (RR) assuming known sample size, outcome rate, exposure prevalence, and 80% power. While there is a paper by Browner and Newman (1989) for sample size and power for the PAF, I think an alternate approach could use the minimum detectable RR that I had already computed and the relationship between the PAF and RR.

risk score

AUC and AUPRC for non-informative or “no-skill” risk score

Published:

Doing some math to show that the area under the receiver-operating characteristic curve (AUROC or AUC) for a non-informative or “no-skill” risk score or classifier (e.g., coin flip) is 0.5, and the area under the precision-recall curve (AUPRC) is the outcome prevalence.

sample size

Power calculations for 1-way ANOVA with possibly unequal group sizes

Published:

I was recently asked to do sample size and power calculations in the setting of a 1-way ANOVA with unequal group sizes. There are solutions to do this when the group sizes are equal, but the answer is not as commonly available for the case where group sizes are unequal.