Sampling Theory Part 2 Flashcards
True or False. The sample size should be carelessly fixed so that it will be adequate to draw valid and generalized conclusions.
False (carelessly - carefully)
What are to be determined in determining the appropriate sample size?
- level of precision
- level of confidence or risk
- degree of variability
True or False. The more the sample size, the more accurate the conclusions and finding is.
True
It is known as sampling error or margin of error.
Level of Precision
It is the range in which the true value of the population is estimated to be.
Level of Precision
True or False. The level of precision is often expressed in fractions.
False(fractions - percentage points)`
It is determined by a statistical method called standard deviation.
Level of Precision
What statistical method is used to determine the level of precision?
standard deviation
It is the spreadness of data.
standard deviation
It refers to how close a measurement is to the true or accepted value.
Accuracy
It refers to how close measurements of the same item are to each other
Precision
True or False. High standard deviation indicates high precision. Low standard deviation indicates low precision.
False (high standard deviation indicates low precision and vice-versa)
It is based on ideas of Central Limit Theorem.
Risk Level of Confidence
When a population is repeatedly sampled, the average value of the attribute obtained by those samples is equal to the true population value.
Central Limit Theorem
These are data that forms a normal curve when graphed.
Parametric
In this, approximately 95% of the sample values are within two standard deviations of the true population value.
Normal Distribution
True or False. If the confidence level is 95%, 5 out of 100 samples will have the true population value within the range of precision specified.
False (5 - 95)
It is the range of values we are fairly sure our true value lies in.
Confidence Level
These are important in solving for confidence interval.
- Sample Mean
- Sample Standard Deviation
- Confidence Level Value
- Sample Size
It refers to the distribution of attributes in the population.
Degree of Variability (Proportion, p)
True or False. The variables with more homogenous population, the larger the sample size required to obtain a given level of precision.
False (larger - smaller)
What is required to obtain a given level of precision with variables with more homogeneous population?
smaller sample size
What is required to obtain a given level of precision with variables with more heterogeneous population?
larger sample size
When assuming the degree of variability, always use _____ for maximum variability, p.
50%
What are the ways in determining the sample size?
- Using census for small populations
- Using sample size of a similar study
- Using published tables
- Using formulas to calculate a sample size
Using this way for determining sample size, we need to eliminate sampling error.
Using census for small population
In this way of determining sample size, we use the entire population as sample.
Using census for small populations
It is favorable when we are considering a small population only.
Using census for small populations
When using this, it may run the risk of repeating errors that were made in determinig the sample size for another study.
Using a sample size of a similar study
It provides the sample size for a given set of criteria.
Using published tables
What are the formulas we can use to determine the sample size?
- Cochran Formula
- Taro Yamane Sampling Formula or Slovin’s Formula
It allows you to calculate an ideal sample size given a desired level of precision, desired confidence level, and the estimated proportion of the attribute present in the population.
Cochran Formula
It is considered especially appropriate in situation with large populations.
Cochran’s Formula
To use this formula, you should be working with a finite population and if the population size is known.
Taro Yamane Formula
