Variability
Numbers that describe diversity or variability in the distribution
What are measures of variability?
The total set of individuals, objects, groups, or events in which the researcher is interested
What is a population?
A type of distribution where the mean is substantially higher than the median.
What is a positively skewed distribution?
A measure (e.g., mean or standard deviation) used to describe the population distribution
What is a population parameter?
The process of identifying and selecting the subset of the population for study
What is sampling?
A measure of variability for nominal variables. It is based on the ratio of the total number of differences in the distribution to the maximum number of possible differences within the same distribution
What is IQV?
A quantitative measure that a particular event will occur
What is a probability?
A bell-shaped and symmetrical theoretical distribution with the mean, the median, and the mode all coinciding at its peak and with the frequencies gradually decreasing at both ends of the curve
What is the normal distribution?
The size of the sample selected from each subgroup is disproportional to the size of that subgroup in the population
What is disproportionate stratified sampling?
The discrepancy between a sample estimate of a population parameter and the real population parameter
What is sampling error?
The width of the middle 50% of the distribution. It is defined as the difference between the lower and upper quartiles (Q1 and Q3). IQR can be calculated for interval-ratio and ordinal data
What is the IQR?
A measure of variation for interval-ratio and ordinal variables; it is the average of the squared deviations from the mean
What is the Variance?
A normal distribution represented in standard (Z) scores
What is a Standard Normal Distribution?
The size of the sample selected from each subgroup is proportional to the size of that subgroup in the entire population
What is proportionate stratified sampling?
A sample designed in such a way as to ensure that (a) every member of the population has an equal chance of being chosen and (b) every combination of N members has an equal chance of being chosen
What is a simple random sample?
A measure of variation in interval-ratio variables. It is the difference between the highest (maximum) and the lowest (minimum) scores in the distribution
What is the Range?
A type of distribution where the mean is substantially lower than the median.
What is a negatively skewed distribution?
A table showing the area (as a proportion, which can be translated into a percentage) under the standard normal curve corresponding to any Z score or its fraction
What is the standard normal table? Appendix B
A specific measure used to describe the sample distribution
What is a sample?
A method of sampling obtained by (a) dividing the population into subgroups based on one or more variables central to our analysis and (b) then drawing a simple random sample from each of the subgroups
What is a stratified random sample?
A measure of variation for interval-ratio and ordinal variables; it is equal to the square root of the variance
What is the Standard Deviation?
A method of sampling in which every Kth member (K is a ratio obtained by dividing the population size by the desired sample size) in the total population is chosen for inclusion in the sample after the first member of the sample is selected at random from among the first members in the population
What is systematic random sampling?
The number of standard deviations that a given raw score is above or below the mean
What is a standard (z) Score?
A method of sampling that enables the researcher to specify for each case in the population the probability of its inclusion in the sample
What is probability sampling?
The standard deviation of the sampling distribution of the mean. It describes how much dispersion there is in the sampling distribution of the mean
What is the standard error of the mean?