LECTURE 6 Flashcards
What is a sample?
A subgroup of the population used in a study.
What is a population in research?
The entire group of interest, such as all psychology students.
What is a sampling frame?
The group from which a sample is chosen, usually a subset of the population.
What is representativeness in sampling?
The extent to which the sample accurately reflects the population.
What is selection bias?
Bias that occurs when the sample is not representative of the population.
What are types of selection bias?
Sampling bias, nonresponse/volunteer bias, and attrition bias
What is sampling bias?
Bias due to an unrepresentative sampling frame.
What is volunteer bias?
Bias when volunteers differ significantly from non-volunteers.
What is attrition bias?
Bias when participants who drop out are different from those who complete the study.
What is random sampling?
Every member of the sampling frame has an equal probability of being chosen.
What is systematic random sampling?
Selecting participants at fixed intervals from a randomized starting point.
What is stratified sampling?
Dividing the population into subgroups and sampling randomly within each subgroup.
What is cluster sampling?
Dividing the population into clusters, then randomly selecting clusters to study.
What is opportunity/convenience sampling?
Selecting participants who are readily available.
What is purposive sampling?
Selecting participants based on specific characteristics or criteria.
What is quota sampling?
Dividing the population into subgroups and filling quotas non-randomly.
What is observation sampling?
Sampling behaviors in specific contexts, such as times, events, or situations.
What is time sampling?
Observing behavior during specific time intervals.
What is event sampling?
Observing specific events within a timeframe.
What is situation sampling?
Observing behaviors in diverse locations or contexts to increase validity.
What is ecological validity?
The extent to which study findings generalize to real-world situations.
What is the sampling distribution?
A theoretical distribution of sample means if infinite samples were drawn from the population.
What is sampling variability?
Differences in sample statistics due to the random selection of samples.
What is the central limit theorem?
The sampling distribution of the mean is always normally distributed, regardless of population distribution.
What is the standard error (SE)?
The standard deviation of the sampling distribution, indicating variability of sample means.
How does sample size affect the standard error?
Larger sample sizes reduce the standard error.
What is a confidence interval?
A range around the sample mean within which the population mean likely falls (e.g., 95% confidence).
How is a confidence interval calculated?
By adding and subtracting 1.96 standard errors from the sample mean for a 95% confidence level.
Why is the value 1.96 used in confidence intervals?
It corresponds to 95% of values in a standard normal distribution.
What is a z-score?
A measure of how many standard deviations a value is from the mean of its distribution.
How is a z-score calculated?
Subtract the mean from the value and divide by the standard deviation.
What is the standard normal distribution?
A normal distribution with a mean of 0 and a standard deviation of 1.
How can z-scores compare different scales?
By standardizing scores from different distributions, making them comparable.
What is the relationship between confidence intervals and sample size?
Smaller sample sizes produce wider confidence intervals.
What is the expected value in sampling?
The mean of the sampling distribution, equal to the population mean.
Why are large samples preferred in inferential statistics?
They reduce sampling variability and provide more accurate estimates of the population.
What is the main takeaway about sampling methods?
Proper sampling ensures representativeness and improves the validity of inferences.
How can sampling bias affect study results?
It can lead to findings that are not generalizable to the target population.
