Statistics How To

Design of Experiments > Grounded Theory What is Grounded Theory? Watch the video for a brief overview or read on to learn more: Can’t see the video? Click here to watch it on YouTube. Grounded theory involves the collection and analysis of data. The theory is “grounded” in actual data, which means the analysis and … Read more

Probability and Statistics > Probability > Fundamental Counting Principle Fundamental Counting Principle Definition. The Fundamental Counting Principle (also called the counting rule) is a way to figure out the number of outcomes in a probability problem. Basically, you multiply the events together to get the total number of outcomes. The formula is: If you have … Read more

Descriptive Statistics > Ogive Graph What is an Ogive Graph? An ogive (oh-jive), sometimes called a cumulative frequency polygon, is a type of frequency polygon that shows cumulative frequencies. In other words, the cumulative percents are added on the graph from left to right. An ogive graph plots cumulative frequency on the y-axis and class … Read more

Statistics Definitions > Cluster Sampling Cluster sampling is used when natural groups are present in a population. The whole population is subdivided into clusters, or groups, and random samples are then collected from each group. When to Use Cluster Sampling Cluster sampling is typically used in market research. It’s used when a researcher can’t get … Read more

Probability and Statistics > Sampling > How to Perform Systematic Sampling Systematic Sampling: Overview One way to get a fair and random sample is to assign a number to every population member and then choose the nth member from that population. For example, you could choose every 10th member, or every 100th member. This method … Read more

Sampling > What is Quota Sampling? Quota sampling is where you take a very tailored sample that’s in proportion to some characteristic or trait of a population. For example, you could divide a population by the state they live in, income or education level, or sex. The population is divided into groups (also called strata) … Read more

Sampling > Sampling design is a mathematical function that gives you the probability of any given sample being drawn. Since sampling is the foundation of nearly every research project, the study of sampling design is a crucial part of statistics, and is often a one or two semester course. It involves not only learning how … Read more

Statistics Definitions > Purposive Sampling / Deliberate Sampling A purposive sample is where a researcher selects a sample based on their knowledge about the study and population. The participants are chosen based on the purpose of the sample, hence the name. As participants are selected according to the needs of the study (hence the alternate … Read more

Hypothesis Testing > Two Tailed Test What is a Two Tailed Test? A two tailed test tells you that you’re finding the area in the middle of a distribution. In other words, your rejection region (the place where you would reject the null hypothesis) is in both tails. For example, let’s say you were running … Read more

Types of Variable > Dichotomous variables are categorical variables with two categories or levels — different groups within the same independent variable. Examples of dichotomous variables Heads or Tails. Male or Female. Rich or Poor. Democrat or Republican. Pass or Fail. Under age 65 or 65 and over. Binary variables are a sub-type of dichotomous … Read more