Random error and systematic error are the two main types of measurement error. Measurement error occurs when the measured value differs from the true value of the quantity being measured. [Read more…] about Random Error vs Systematic Error

# Basics

## Dunning Kruger Effect: Definition & Examples

## What is the Dunning Kruger Effect?

The Dunning-Kruger effect is a cognitive bias that causes people with low abilities or knowledge to overestimate themselves compared to others. Conversely, people with high skills tend to underestimate themselves. In short, it is a psychological phenomenon that distorts our self-evaluation. [Read more…] about Dunning Kruger Effect: Definition & Examples

## What is a Ratio and Proportion?

Ratios and proportions are related concepts in mathematics and statistics. A ratio compares two quantities and shows their relative sizes. For example, a veterinary office might have 1 dog to 2 cats as patients. This comparison tells us that they see twice as many cats as dogs. [Read more…] about What is a Ratio and Proportion?

## Confirmation Bias Definition and Examples

## What is Confirmation Bias?

Confirmation bias is the tendency to seek information confirming preexisting beliefs while ignoring information contradicting them. This bias can be particularly problematic when making important decisions, leading to flawed reasoning and inaccurate conclusions. It is a type of cognitive bias. [Read more…] about Confirmation Bias Definition and Examples

## Cognitive Bias: Definition & Examples

## What is Cognitive Bias?

A cognitive bias is a systematic fault in thinking and decision-making that can affect our judgments and perceptions. These biases can arise due to our limited mental capacity, the complexity of the environment, and the influence of our prior experiences and beliefs. [Read more…] about Cognitive Bias: Definition & Examples

## Sampling Frame: Definition & Examples

## What is a Sampling Frame?

A sampling frame lists all members of the population you’re studying. Your target population is the general concept of the group you’re assessing, while a sampling frame specifically lists all population members and how to contact them. It might also include demographic information for each person because some methods, such as stratified sampling, require it. [Read more…] about Sampling Frame: Definition & Examples

## Using Scientific Notation

## What is Scientific Notation?

Scientific notation is a compact way of writing numbers that are too large or too small to be conveniently written in decimal form. It is a shorthand letting us write numbers using powers of 10. Scientific fields such as astronomy, physics, chemistry, and statistics frequently use scientific notation.

Below is an example of shorthand notation:

- 3.2 X 10
^{8} - 3.2 X 10^8
- 3.2E8

All three forms of scientific notation are equivalent. In the last format, the E stands for exponent.

In this blog post, you’ll learn how to interpret scientific notation, convert numbers to this format, and how to use it for multiplication and division. [Read more…] about Using Scientific Notation

## Selection Bias: Definition & Examples

## What is Selection Bias?

Selection bias occurs when researchers make decisions that cause a sample to be systematically different from the population of interest.

Selection bias can arise from various decisions, such as:

- Using an improper sampling method.
- Making particular methodology and data choices.
- Choosing a study design that affects the continued participation of subjects.

[Read more…] about Selection Bias: Definition & Examples

## Fibonacci Sequence: Formula & Uses

## What is the Fibonacci Sequence?

The Fibonacci sequence is a series of numbers that appears in surprisingly many aspects of nature, from the branching of trees to the spiral shapes of shells. This series is named after the Italian mathematician Leonardo Fibonacci. [Read more…] about Fibonacci Sequence: Formula & Uses

## Undercoverage Bias: Definition & Examples

## What is Undercoverage Bias?

Undercoverage bias occurs when the population list from which the researchers select their sample (aka the sampling frame) does not include all population members. When that happens, the sample cannot contain the unlisted individuals, potentially producing a biased sample that doesn’t fully represent the population. [Read more…] about Undercoverage Bias: Definition & Examples

## Matched Pairs Design: Uses & Examples

## What is a Matched Pairs Design?

A matched pairs design is an experimental design where researchers match pairs of participants by relevant characteristics. Then the researchers randomly assign one person from each pair to the treatment group and the other to the control group. This type of experiment is also known as a matching pairs design. [Read more…] about Matched Pairs Design: Uses & Examples

## Nonresponse Bias: Definition & Reducing

## What is Nonresponse Bias?

Nonresponse bias occurs when people who do not participate in a survey or study have different characteristics or opinions than those who do participate. In this situation, the sample data overrepresent the subpopulations who tend to respond instead of reflecting the whole population. [Read more…] about Nonresponse Bias: Definition & Reducing

## Slope Intercept Form of Linear Equations: A Guide

## What is Slope Intercept Form?

The slope intercept form of linear equations is an algebraic representation of straight lines: y = mx + b. [Read more…] about Slope Intercept Form of Linear Equations: A Guide

## Population vs Sample: Uses and Examples

## What is a Population vs Sample?

Population vs sample is a crucial distinction in statistics. Typically, researchers use samples to learn about populations. Let’s explore the differences between these concepts! [Read more…] about Population vs Sample: Uses and Examples

## How to Calculate a Percentage

Calculating percentages is a standard mathematical procedure. A percent is a ratio that you write as a fraction of 100. In this article, learn why percentages are crucial summary measures and how to calculate them. [Read more…] about How to Calculate a Percentage

## Principal Component Analysis Guide & Example

## What is Principal Component Analysis?

Principal Component Analysis (PCA) takes a large data set with many variables per observation and reduces them to a smaller set of summary indices. These indices retain most of the information in the original set of variables. Analysts refer to these new values as principal components. [Read more…] about Principal Component Analysis Guide & Example

## Percent Change: Formula and Calculation Steps

Percent change is the relative difference between an old value and a new value. Positive values represent an increase over time, while negative numbers indicate a reduction.

For example, if the price of a candy bar changes from $1 to $1.10, it’s a 10% increase. [Read more…] about Percent Change: Formula and Calculation Steps

## Simpsons Paradox Explained

## What is Simpsons Paradox?

Simpsons Paradox is a statistical phenomenon that occurs when you combine subgroups into one group. The process of aggregating data can cause the apparent direction and strength of the relationship between two variables to change. [Read more…] about Simpsons Paradox Explained

## Weighted Average: Formula & Calculation Examples

## What is a Weighted Average?

A weighted average is a type of mean that gives differing importance to the values in a dataset. In contrast, the regular average, or arithmetic mean, gives equal weight to all observations. The weighted average is also known as the weighted mean, and I’ll use those terms interchangeably. [Read more…] about Weighted Average: Formula & Calculation Examples

## Concurrent Validity: Definition, Assessing & Examples

## What is Concurrent Validity?

Concurrent validity is the degree to which assessment scores correlate with a criterion variable when researchers measure both variables at approximately the same time (i.e., concurrently). This method validates an assessment instrument by comparing its scores to another test or variable that researchers had validated previously. [Read more…] about Concurrent Validity: Definition, Assessing & Examples