Science Olympiad Disease Detectives Formulas

What is the formula for Herd Immunity Threshold?

(1 - [1/R0]) * 100%

What does R₀ stand for in the Herd Immunity Threshold formula?

The basic reproduction number; the average number of new cases generated by one infected person in a fully susceptible population.

What is the formula for Incidence rate?

# of new cases of disease during a specific time period / # of people at risk.

What is the formula for Prevalence?

Total # of cases (old & new) / # of people at risk

What is the formula for Sensitivity?

TP / (TP + FN)

What is the formula for Specificity?

TN/(TN + FP)

What is the formula for PPV/Positive Predictive Value?

TP/(TP+FP)

What is the formula for NPV/Negative Predictive Value?

TN/(FN+TN)

What is the formula for Relative Risk/Risk Ratio/Incidence Ratio?

(a / [a + b]) / (c / [c + d])

What is the formula for Relative Risk Reduction?

1 - Relative Risk

What is the formula for point prevalence?

Number of cases in a defined population at one point in time / Number of people in a defined population at the same point in time.

What is the formula for Attack Rate?

(Total # of new cases of a disease / total population at risk) * 100%

What is the formula for Chi-square?

The sum of (O - E) sqaured / E

What is the formula for Confidence Interval?

sample mean plus or minus (Z * SE)

What is the formula for Odds Ratio?

ad / bc

What is the formula for Secondary Attack Rate?

([Total # of cases - Initial case of a disease] / total population at risk) * 100%

What is the formula for Age Specific Mortality Rate?

(Total # of Deaths in age group / Total Population at risk in age group x) * population multiplier

What is the formula for Morbidity Rate?

# of nonfatal new cases / Population at risk

What is the formula for Case-fatality?

# of deaths / # of new cases

What is the formula for Crude death rate?

(# of deaths in 1 year / mid year population) * population multiplier

What is the formula for Infant mortality rate?

(# of deaths < 1 yr. of age / # of live births) * population multiplier

What does the O in the Chi-Square formula mean?

Observed frequencies.

What does the E in the Chi-Square formula mean?

Expected frequencies

What does the Z in the Confidence Interval formula mean?

Confidence level value.

What does the SE in the Confidence Interval formula mean?

Standard error of the sample mean.

What is the formula for Standard error of the sample mean?

standard deviation / the square root of the sample size