2022 Introduction to Statistics in Research Mitchell 2nd ed

I N T R O T O R E S E A R C H : D A T A V I S U A L I Z A T I O N & C O M M O N S T A T T E S T S

Outlier: An outlier is an observation this is many standard deviations from the mean. Outliers should always be investigated to find the cause. Otherwise, discarding outliers may cause the research to underestimate the true variability. P -value: a probability value of observing a sample value as extreme as or more extreme than, the value observed, given that the null hypothesis is true. For example, the p-value of a null hypothesis is set by the researcher used to measure the significance level in which to reject the null hypothesis. The p-value for many tests is .05, but the set value will depend on the study (for example, if you are testing the quality of medical devices, your p-value might be .001). Pareto diagram: a graphical presentation that represents frequency data as a bar chart, ordered from most to least, overlaid with a line graph denoting the cumulative percentage at each variable level. This diagram separates the significant problems from the trivial. Pearson correlation coefficient: the r symbolizes the estimate of the strength of linear association and its direction between interval and ratio variables; a range of +1 to -1. The sign indicates the direction and the number indicates the strength of the relationship.

Pictograph: a bar chart using pictorial symbols rather than bars to represent frequency data. One symbol unit represents a specific count of that variable.

Pretesting: the procedure for assessing questions and instruments before the start of the study to discover errors in questions, question sequencing errors, instruction errors, etc.

Poisson Distribution : a distribution is a discrete probability distribution that depends on one parameter.

Population: All the cases associated with a defined group. The elements about which we wish to make some inferences.

Post hoc ergo propter hoc: “After this, therefore because of this” – a fallacy of logic. For example inferring a causal relationship from correlation.

Probability: the probability (chance) of an event is a number between zero and 100%.

Probability Sampling (and non-probability sampling): Most researchers want the sample to represent the entire population. Sampling methods are generally divided into two categories of probability sampling and non-probability sampling. In probability sampling, each member has a known opportunity to belong to the sample. In non-probability sampling, there is no specific probability of the individual to be part of the sampling. Projective techniques: a qualitative method that encourages participants to reveal hidden or suppressed attitudes, ideas, emotions, and motives. Various techniques fall under this method – sentence completion tests, cartoon or balloon tests, word association, etc. Prospective observational study: A prospective observational study is forward-looking. An example would be looking for outcomes (such as the development of a disease) during the study period relating this to other factors such as suspected risk or protection factors. The study usually takes a long time (as in 20 years!)

48