Week 3: Descriptive Statistics, Probability, and Measures of Central Tendency

Central Tendency

Indicator of the centre of data

Mode

The most frequently occurring value or category in the distribution. When a unimodal distribution has only one mode, it is called .

Binomial

Having two values or categories that have the highest occurrence and that are equal frequencies.

Extreme Outlier

An outlier in a data set that is more than 3 times the interquartile range either above or below the interquartile range (±3 × the length of the box above or below the box on a box and whiskers plot).

Frequency Distribution

Lists all the possible outcomes of an experiment and tallies the number of times each outcome occurs.

Mean

The sum of the values divided by the total number of observations. It is the most commonly known measure of central tendency but requires interval or ratio data. Can not be used to calculate ordinal or nominal data.

Median

For ordinal, interval, and ratio data, the value in the middle when all the measured values are lined up in order from least to most; the 50th percentile value.

Multimodal

Having more than two modes.

Normal distribution

“68%,95%, 99%” A probability distribution in which the mean, median, and mode are equal, with a bell-shaped distribution curve.

Probibility

The chance that a particular outcome will occur after an event.

Probability distribution

The probability of all the possible outcomes of the variable.

p-Value

The probability of finding the reported results if the null hypothesis is true.

Range

The difference between the maximum and minimum values in a distribution.

Sampling Distribution

Plots realized frequencies of a statistic versus the range of possible values that statistic can take.

Skewed distribution

An asymmetrical distribution of the values of the variable around the mean, making one tail longer than the other.

Standard deviation

The average distance that the values in a distribution are from the center.

Turkey fences

A cutoff value indicating that an observation is an outlier in a data set because it is more than 1.5 times the interquartile range either above or below the interquartile range (±1.5 times the length of the box above or below the box on a box and whiskers plot).

Z-score

A measure that indicates how many standard deviations a value is from the mean value.

Null-hypothesis

Where you sample is an ideal reflection of the population.

Variable

An operational diffrence

Range

The difference between the maximum and minimum values.

Varience

The average of squared differences from the mean.

Table 1

Usually the first table in a research study, Describes the sample

Descriptive studies

Track trends of diseases over time

Healthcare resource planning

Safety outcome monitoring

Hypothesis generation