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132 results for "Deborah J. Rumsey"

Figuring Out What Probability Means
Probabilities come in many different disguises. Some of the terms people use for probability are chance, likelihood, odds, percentage, and proportion. But the basic definition of [more…]
Found in: Math 
Generalizing Statistical Results to the Entire Population
Making conclusions about a much broader population than your sample actually represents is one of the biggest nono's in statistics. This kind of problem is called [more…]
Found in: Statistics 
Statistics Conundrums: Dealing with Survey Nonresponders
Nonresponders are always a problem when you're calculating the results of a survey. Before you can crunch the numbers in all the surveys you get back, you have to decide what to do about the surveys you [more…]
Found in: Statistics 
Using Probability When Hitting the Slot Machines
Remember the movie National Lampoon's Vegas Vacation, when gambling fever consumes Chevy Chase's character, Clark W. Griswold? He goes on a losing streak to beat all losing streaks while his son, Rusty [more…]
Found in: Math 
How to Determine Which Data Analysis to Use in Statistics II
Statistics II is often about data analysis, and the trick is to know when to use which analysis method. The following table helps you compare, contrast, and decide what data analysis to use and when. Use [more…]
Found in: Statistics 
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 [more…]
Found in: Statistics 
Tips for Statistics Test Success
Working on statistics problems (especially word problems) can be frustrating; but it doesn’t have to be! You just have to avoid the urge to jump right in and start doing calculations because the key to [more…]
Found in: Statistics 
Statistical Standard Scores and Standard Normal Distributions — The “ZTable”
Statistics are handy when it comes to making predictions, but to make accurate predictions, you need to know how reliable your results are. The following Z table shows standard scores and percentiles [more…]
Found in: Statistics 
Statistical TDistribution — The “TTable”
As a statistical tool, a ttable lists critical values for twotailed tests. You then use these values to determine confidence values. The following ttable shows degrees of freedom for selected percentiles [more…]
Found in: Statistics 
Continuous Probability Distributions
When you work with continuous probability distributions, the functions can take many forms. These include continuous uniform, exponential, normal, standard normal [more…]
Found in: Probability 
Probability Study Tips
If you're going to take a probability exam, you can better your chances of acing the test by studying the following topics. They have a high probability of being on the exam. [more…]
Found in: Probability 
Principles of Probability
The mathematics field of probability has its own rules, definitions, and laws, which you can use to find the probability of outcomes, events, or combinations of outcomes and events. To determine probability [more…]
Found in: Probability 
Discrete Probability Distributions
In probability, a discrete distribution has either a finite or a countably infinite number of possible values. That means you can enumerate or make a listing of all possible values, such as 1, 2, 3, 4, [more…]
Found in: Probability 
Understanding Formulas for Common Statistics
After data has been collected, the first step in analyzing it is to crunch out some descriptive statistics to get a feeling for the data. For example: [more…]
Found in: Statistics 
Statistically Figuring Sample Size
When designing a study, the sample size is an important consideration because the larger the sample size, the more data you have, and the more precise your results will be [more…]
Found in: Statistics 
Surveying Statistical Confidence Intervals
In statistics, a confidence interval is an educated guess about some characteristic of the population. A confidence interval contains an initial estimate plus or minus a [more…]
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* [more…]
Found in: Statistics 
Handling Statistical Hypothesis Tests
You use hypothesis tests to challenge whether some claim about a population is true (for example, a claim that 40 percent of Americans own a cellphone). To test a statistical hypothesis, you take a sample [more…]
Found in: Statistics 
How to Calculate the Margin of Error for a Sample Mean
When a research question asks you to find a statistical sample mean (or average), you need to report a margin of error, or MOE, for the sample mean. The general formula for the margin of error for the [more…]
Found in: Variance & Margin of Error 
How to Find Percentiles for a tDistribution
When you want to find percentiles for a tdistribution, you can use the ttable. A percentile is a number on a statistical distribution whose lessthan probability is the given percentage; for example, [more…]
Found in: Binomial, Normal & tDistributions 
How to Find t*Values for Confidence Intervals
Confidence intervals estimate population parameters, such as the population mean, by using a statistic (for example, the sample mean) plus or minus a margin of error. To compute the margin of error for [more…]
Found in: Binomial, Normal & tDistributions 
How to Identify a Sampling Distribution
In statistics, a sampling distribution is based on sample averages rather than individual outcomes. This makes it different from a distribution. Here’s why: A [more…]
Found in: Binomial, Normal & tDistributions 
How Sample Size Affects Standard Error
Standard error is inversely affected by the size, n, of a statistical sample. Because n is in the denominator of the standard error formula, the standard error decreases as [more…]
Found in: Binomial, Normal & tDistributions 
How Population Standard Deviation Affects Standard Error
In statistics, an important component of standard error involves the amount of variability in the population (measured by standard deviation). In the standard error formula [more…]
Found in: Binomial, Normal & tDistributions 
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 [more…]
Found in: Binomial, Normal & tDistributions