Search Results

143 results for "Deborah J. Rumsey"

• Statistics Tables for Reference

Several commonly used tables in statistics include the Z-table, the t-table, the binomial table, and a table of z*-values for selected confidence levels. Excerpted from

• Computer Output for Statistics II

If you’re taking Statistics II, you’re likely to face questions on computer output for multiple regression and ANOVA. Professors like to give output on exams and ask you to interpret it. Sometimes they

Found in: Statistics
• How to Find Percentiles for a t-Distribution

When you want to find percentiles for a t-distribution, you can use the t-table. A percentile is a number on a statistical distribution whose less-than probability is the given percentage; for example,

• How Sample Size Affects Standard Error

The size (n) of a statistical sample affects the standard error for that sample. Because n is in the denominator of the standard error formula, the standard error decreases as

• Using Linear Regression to Predict an Outcome

Statistical researchers often use a linear relationship to predict the (average) numerical value of Y for a given value of X using a straight line (called the

• How to Find the Interquartile Range for a Statistical Sample

To obtain a measure of variation based on the five-number summary of a statistical sample, you can find what's called the interquartile range, or IQR.

The purpose of the five-number summary is to give descriptive

• How a Pie Chart Reflects Categorical Data in a Statistical Data Set

A pie chart takes categorical data from a statistical sample and breaks them down by group, showing the percentage of individuals that fall into each group. Because a pie chart takes on the shape of a

• What the Distribution Tells You about a Statistical Data Set

The distribution of a statistical data set (or a population) is a listing or function showing all the possible values (or intervals) of the data and how often they occur. When a distribution of categorical

• Avoid Drawing the Wrong Conclusions from Statistical Data

Statistical formulas don’t know whether they are being used properly, and they don’t warn you when your results are incorrect. In order to draw the appropriate conclusions, it’s up to you to avoid overstating

• How to Interpret the Margin of Error in Statistics

You’ve probably heard or seen results like this: “This statistical survey had a margin of error of plus or minus 3 percentage points.” What does this mean? Most surveys are based on information collected

• How to Find Right-Tail Values and Confidence Intervals Using the t-Table

You can use a t-table to find right-tail probabilities and p-values for hypothesis tests and to find t*-values (critical values) for a confidence interval involving

• How to Identify the Notation for the Mean and Variance of a Discrete Random Variable

Two of the most important terms in statistics are mean and variance, and so you need to be able to identify their notations when working with discrete random variables.

• How to Tell a Z-Distribution from a t-Distribution

Although the normal (Z-) distribution and t-distribution are similar, they look different from each other and are used for different statistical purposes. The normal distribution is that well-known bell-shaped

• How z-Values Are Used in Statistics

If a statistical data set has a normal distribution, it is customary to standardize all the data to obtain standard scores known as z-values or z-scores. The distribution of

• How to Find Probabilities for a Sample Mean

In statistics, you can easily find probabilities for a sample mean if it has a normal distribution. Even if it doesn’t have a normal distribution, or the distribution is not known, you can find probabilities

• How to Interpret a Scatterplot

Scatterplots are useful for interpreting trends in statistical data. Each observation (or point) in a scatterplot has two coordinates; the first corresponds to the first piece of data in the pair

• How to Determine a p-Value When Testing a Null Hypothesis

When you test a hypothesis about a population, you can use your test statistic to decide whether to reject the null hypothesis, H0. You make this decision by coming up with a number, called a

• Statistics For Dummies Cheat Sheet

Whether you’re studying for an exam or just want to make sense of data around you every day, knowing how and when to use data analysis techniques and formulas of statistics will help. Being able to make

Found in: Statistics
• Checking Out Statistical Confidence Interval Critical Values

Critical values (z*-values) are an important component of confidence intervals (the statistical technique for estimating population parameters). The z*

Found in: Statistics
• How to Calculate a Regression Line

In statistics, you can calculate a regression line for two variables if their scatterplot shows a linear pattern and the correlation between the variables is very strong

• Working with Statistical Two-Way Tables

To explore the links between two categorical variables, you first need to organize the data that’s been collected, and a table is a great way to do that. A

• Applying the Empirical Rule (68-95-99.7) to a Statistical Data Set

The Empirical Rule (68-95-99.7) says that if the population of a statistical data set has a normal distribution (where the data are in the shape of a bell curve) with population mean

• Avoid Bias with Random Statistical Samples

How do you select a statistical sample in a way that avoids bias? The key word is random. A random sample is a sample selected by equal opportunity; that is, every possible sample of the same size as yours

• Describing Your Statistical Data with Numbers

After collecting good statistical data, you can summarize it with descriptive statistics. These are numbers that describe a data set in terms of its important features:

• How to Identify Skew and Symmetry in a Statistical Histogram

Sometimes the mean versus median debate can get quite interesting. Especially when you look at the skewness and symmetry of your statistical data in a histogram.

8 results for "Deborah J. Rumsey" in the store

 About us More From Dummies Topics A-Z