4/11/2023 0 Comments Observation definitionObservationsĭata points in a given data set. ![]() Normal DistributionĪ bell-shaped curve or distribution indicating that observations at or close to the mean occur with highest probability, and that the probability of occurrence progressively decreases as observations deviate from the mean. The most common value in any distribution. The middle item in a group of data when the data are ranked in order of magnitude. The arithmetic average for a group of data. The largest observation in a set of data. The smallest observation in a set of data. Statistics designed to represent the average or middle in a distribution of data. Sometimes, the difference in the value of the measurement of interest for each matched pair is calculated, for example, the difference between before and after measurements, and these figures then form a single sample for an appropriate statistical analysis. Examples include the times of a group of athletes for 1500m before and after a week of special training or the milk yields of cows before and after being fed a particular diet. Those samples in which the same attribute, or variable, is measured twice on each subject, under different circumstances.For example, IQ measurements on pairs of identical twins. Two samples in which the members are clearly paired, or are matched explicitly by the researcher.Matched samples can arise in the following situations: Using sample statistics to infer characteristics about the population. The variable that causes or predicts the dependent variable. However, if you were to measure one child's height over time, these observations would be dependent because the height at each time point would affect the height at future time points. A simple example is measuring the height of everyone in your sample at a single point in time. Two observations are independent if the occurrence of one observation provides no information about the occurrence of the other observation. Examples range from comparing males and females as two independent samples within a population to comparing a treatment group to a control group in an interventional study. Or to restate the same principle, if you know the outcome for one sample, it will provide you with no information about the outcome for the other sample. The outcome for one sample is assumed to be unrelated to the outcomes for each of the other samples. Independent samples are two or more samples selected from the same population, or different populations, that have no effect on one another. See Hypothesis Testing in Advanced Statistical Topics. Frequency ChecksĬreating a table that shows a body of data grouped according to numerical values.Ī bar graph representing a frequency distribution. ![]() Numerical designations of how closely data cluster about the mean or other measure of central tendency. Statistics used to summarize a body of data Dispersion For example, you might want to see how many observations occur by age, gender, city, etc. Cross TabulationsĬomparing two or more variables of data. For example height, weight, temperature, the amount of sugar in an orange, and the time required to run a mile are all continuous variables. ![]() ![]() Continuous VariableĪ variable that can take on any value. See Confidence Intervals in Advanced Statistical Topics. The upper and lower boundaries that one is X percent sure the estimate falls within (as in 95% confidence limits). First treatment provided might have the values of 'IV line' and 'Airway inserted,' among others (also nominal). For example, patient sex can take on the values of male or female. Statistical Terms Dictionary Index: A-G | H-L | M-Z Categorical VariableĪ variable is categorical if its values fall into a distinct set of categories that do not overlap.
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