Basic Statistics Concepts #1

When we start learning Statistics, our first plan of action is to learn the basic statistics concepts used in this field. The most common question asked by new students is “What is Statistics?”. Statistics is the inferential study of data from a sample to estimate the behavior and characteristics of a population defined by the the study.

Here are some basic statistics concepts

The beginning of any statistical study starts with the definition of a population.

Population

A population is the whole set of the defined boundaries of our conditions. For Example. A population of Adults in the country. This statement has defined boundaries. namely Country and Adult. So this is a count of all the people who are above the age of 18 (or 21 in some countries) in a specific country. In statistical studies we always want to study and get results about the population. However, in most cases the populations are so vast that it becomes impossible to get data from it.

Sample

A sample is a finite amount and a subset of the defined population in the statistical study. We do the statistical calculations on a sample. These calculations help us predict how the population is affected under the definition of the study. You will note soon enough that the accuracy of the study will increase as the sample size increases. For example. A randomly selected sample of adults from a cinema to give reviews of a movie. If this reminds you of anything then basically if 20 people out of 50 people like a movie then we can draw a conclusion that 40% like the movie and 60% dislike it.

Parameter

A parameter is a property of the population. These are values that may be calculated or hypothesized. Population mean, Population Variance are some of the examples.

Statistic

A Statistic is a property of the sample. Sample mean, sample variance, median, mode are some of the Statistics of a sample.

Mean

This is the average value of the collected sample in the statistical study. When talking about the population mean this may be a census based or survey based value, or a hypothesized value. The sample mean can be calculated with the following formula:

mean formula-basic statistics concepts

Median

A median is the that is in the center of the data. This indicates that half of the data points are below it and half of the data points are above it. The location of the Median in relation to the mean indicates the observer to the shape of the distribution. The sample median formula changes depending on the sample size.

If the sample has odd numbers then Formula for median is:

median formula 1- basic statistics concepts

For a sample size of 37, the Median will be the 19th value.

If the sample has even numbers then the formula for median consists of 3 steps:

median formula2 - basic statistics concepts

Example: A sample consists of the numbers 1 to 40. The sample size is 40. the (n/2)th value is 20. the ((n+1)/2)th value is 20. The mean of these 2 values is 20.5. The median will be 20.5 for that sample.

Frequency

Samples in statistical studies are mostly selected at random. There are usually values that repeat themselves. For example: If you select 50 students at random in a school. There will be a possibility that some students will have the same age. The number of students having the same age is the Frequency of that age.

Mode

When there are multiple values with different frequencies in a sample, the number with the highest frequency is known as the mode of the sample. If there are no repeating values in a sample then There is no Mode. If a sample has multiple values having the same frequency then they are all listed as the mode with a comma separation.

These are the Basic Statistics Concepts to get started in learning this field. Please check this website for global statistical data on various topics such as world populations, births in a year, cars manufactured and many more. We will pick out some samples from this link and calculate some basic statistics in the future.

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