Home
Back
Observed Frequency Formula:
| From: | To: |
Observed Frequency (OF) is a statistical measure used in contingency tables to calculate the expected count for each cell. It represents the frequency we would expect to see in each category if there was no association between the variables.
The calculator uses the Observed Frequency formula:
Where:
Explanation: This formula calculates the expected frequency for a cell in a contingency table by multiplying the row total by the expected value and dividing by the grand total.
Details: Calculating observed frequencies is essential for statistical tests like chi-square tests, which determine if there's a significant association between categorical variables in contingency tables.
Tips: Enter the expected value (E), row total (RT), and grand total (GT). All values must be valid (non-negative, GT > 0).
Q1: What is the difference between observed and expected frequency?
A: Observed frequency is the actual count in each category, while expected frequency is the theoretical count we would expect if there was no association between variables.
Q2: When should I use this calculation?
A: This calculation is primarily used in chi-square tests of independence to analyze contingency tables and determine if variables are related.
Q3: What does a large difference between observed and expected frequencies indicate?
A: A large difference suggests a potential association between the variables being studied, which may be statistically significant.
Q4: Can this formula be used for any size contingency table?
A: Yes, this formula works for 2x2 tables as well as larger contingency tables, though the interpretation may vary based on table size.
Q5: What are the assumptions behind this calculation?
A: The main assumptions are that observations are independent, and expected frequencies should be greater than 5 for most cells to ensure validity of chi-square tests.