Question about expected frequencies

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To find the expected frequency, you can use the formula (upper limit - lower limit)/2 multiplied by the observed frequency for each range. In summary, the ranges have different observed frequencies and the mean and standard deviation can be calculated, but the expected frequency for each range is simply the observed frequency.
  • #1
chuy52506
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Say I have ranges:
(-infinity to 16) where the observed frequency is 35
(16 to 18) where the obs freq is 100
(18 to 20) where the obs.. freq. is 360
(20 to 22) where the obs. freq. is 326
(22 to 24) where the obs. freq. is 150
(24 to infinity) where the obs freq is 29

The mean is 20 and standard deviation is 2

How would i find the expected value of each range?
 
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  • #2
You really can't. For all except the end ranges a good estimate is the midpoint. For the two ends there is not much you can do.
 
  • #3
sorry i meant to ask how do you find the expected frequency not value?
 
  • #4
chuy52506 said:
sorry i meant to ask how do you find the expected frequency not value?
The best estimate for the expected frequency is the observed frequency.
 
  • #5


To find the expected value of each range, you would need to use the formula for expected frequency, which is the total number of observations multiplied by the probability of an observation falling within that range. In this case, the total number of observations is 1000 (35+100+360+326+150+29), and the probability for each range can be calculated by dividing the observed frequency for that range by the total number of observations. For example, the probability for the range (-infinity to 16) would be 35/1000 = 0.035. Then, to find the expected value for that range, you would multiply 0.035 by 1000, which gives you an expected frequency of 35 for that range. You would repeat this process for each range to find the expected frequency for each range.
 

Related to Question about expected frequencies

1. What is meant by expected frequencies in scientific research?

Expected frequencies refer to the number of times a particular outcome or event is expected to occur in a study or experiment based on statistical probability. It is often compared to the actual frequencies observed in the data to determine if there is a significant difference between the two.

2. How do you calculate expected frequencies?

Expected frequencies can be calculated using a variety of statistical methods, such as the chi-square test or the binomial distribution. These methods take into account the sample size, probability, and other relevant factors to determine the expected number of occurrences for a particular outcome.

3. Why is it important to consider expected frequencies in research?

Expected frequencies help researchers to understand the likelihood of certain outcomes or events in a study, and to determine if there are any significant differences between the expected and observed frequencies. This can provide valuable insights into the data and help to draw more accurate conclusions.

4. Can expected frequencies be used to make predictions?

Expected frequencies are based on statistical probability and can be used to make predictions about the likelihood of certain outcomes or events occurring in future studies or experiments. However, it is important to note that these predictions are not guaranteed and may vary depending on the specific conditions and variables of each study.

5. How can unexpected frequencies impact the results of a study?

If the observed frequencies in a study vary significantly from the expected frequencies, it may indicate that there are other factors or variables influencing the outcome. This can impact the validity and reliability of the results and may require further investigation or adjustment of the research methods.

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