What is a 'ZTest'
A Ztest is a statistical test used to determine whether two population means are different when the variances are known and the sample size is large. The test statistic is assumed to have a normal distribution and nuisance parameters such as standard deviation should be known in order for an accurate ztest to be performed.
BREAKING DOWN 'ZTest'
A onesample location test, twosample location test, paired difference test and maximum likelihood estimate are examples of tests that can be conducted as ztests. Ztests are closely related to ttests, but ttests are best performed when an experiment has a small sample size. Also, ttests assume that the standard deviation is unknown, while ztests assume that it is known. If the standard deviation of the population is unknown, the assumption that the sample variance equals the population variance is made.

TTest
A statistical examination of two population means. A twosample ... 
Analysis Of Variance  ANOVA
A statistical analysis tool that separates the total variability ... 
Standard Error
The standard deviation of the sampling distribution of a statistic. ... 
Sampling
A process used in statistical analysis in which a predetermined ... 
Homoskedastic
A statistics term indicating that the variance of the errors ... 
Budget Variance
A periodic measure used by governments, corporations or individuals ...

Investing
What's a TTest?
TTest is a term from statistics that allows for the comparison of two data populations and their means. The test is used to see if the two sets of data are significantly different from one another. ... 
Fundamental Analysis
Explaining Variance
Variance is a measurement of the spread between numbers in a data set. 
Fundamental Analysis
How Does Sampling Work?
Sampling is a term used in statistics that describes methods of selecting a predefined representative number of data from a larger data population. 
Economics
What is Systematic Sampling?
Systematic sampling is similar to random sampling, but it uses a pattern for the selection of the sample. 
Forex Education
Trading With Gaussian Models Of Statistics
The entire study of statistics originated from Gauss and allowed us to understand markets, prices and probabilities, among other applications. 
Markets
The Uses And Limits Of Volatility
Check out how the assumptions of theoretical risk models compare to actual market performance. 
Fundamental Analysis
Explaining the Empirical Rule
The empirical rule provides a quick estimate of the spread of data in a normal statistical distribution. 
Fundamental Analysis
What is a Representative Sample?
In statistics, a representative sample accurately represents the makeup of various subgroups in an entire data pool. 
Economics
Understanding Statistics
Statistics provide the means to analyze data and then summarize it into a numerical form. 
Fundamental Analysis
Explaining the Central Limit Theorem
Central limit theorem is a fundamental concept in probability theory.

What assumptions are made when conducting a ttest?
Learn what a ttest is, and discover the five standard assumptions that are made regarding the validity of sampling and data ... Read Answer >> 
What is the difference between standard deviation and variance?
Understand the difference between standard deviation and variance; learn how each is calculated and how these concepts are ... Read Answer >> 
How is standard deviation used to determine risk?
Understand the basics of calculation and interpretation of standard deviation and how it is used to measure risk in the investment ... Read Answer >> 
What is the difference between standard deviation and mean?
Understand the basics of calculating and interpreting mean and standard deviation and how these mathematical fundamentals ... Read Answer >> 
How is an unfavorable variance discovered?
Learn how unfavorable variance is discovered through defining budget numbers, such as standard rates for labor and materials, ... Read Answer >> 
What is the difference between expected return and variance?
Learn about expected return and variance, the difference between the two measures and how to calculate the expected return ... Read Answer >>