If you’re looking for help with probability and statistics, you’re in the right place. StatisticsHowTo.com has a comprehensive database of articles covering all the material you’re likely to find in an AP statistics, elementary statistics or college statistics class. Several hundred articles include short, how-to videos that you can also find on our YouTube Channel.

### Probability and Statistics Topic Indexes

- Basic Statistics.
- Descriptive Statistics: Charts, Graphs and Plots.
- Probability.
- Binomial Probability Distributions.
- Definitions for Common Statistics Terms.
- Critical Values, Z-Tables and Hypothesis Testing.
- Normal Distributions.
- T-Distributions.
- Central Limit Theorem.
- Confidence Intervals.
- Chebyshev’s Theorem.
- Sampling and Finding Sample Sizes.
- Chi Square.
- Online Tables (z-table, chi-square, t-dist etc.).
- Regression Analysis / Linear Regression.
- Non Normal Distributions.

### Technology Topic Indexes

- Online calculators.
- Microsoft Excel for Statistics.
- TI 83 for elementary statistics.
- TI 89 for elementary statistics.
- SPSS Statistics.
- Minitab for Statistics.
- Statistics Help.
- What is the best calculator for statistics?

## Pre-Statistics

## What is Probability and Statistics?

Probability and Statistics usually refers to an introductory course in probability and statistics. The “probability” part of the class includes calculating probabilities for events happening. While it’s usual for the class to include basic scenarios like playing cards and dice rolling at first, these basic tools are used later in the class to find more complex probabilities, like the probability of contracting a certain disease. The “statistics” part of probability and statistics includes a wide variety of methods to find actual statistics, which are numbers you can use to generalize about a population. For example, you could calculate the height of all your male classmates and find the mean height to be 5’9″ — this is a statistic. But then you could take that statistic and say “I think the average height of an American male is 5’9″ “. How accurate your guess is depends on many factors, including how many men you measured and how many men are in the entire population. Statistics are useful because we often don’t have the resources to measure, survey or poll every member of a population, so instead we take a sample (a small amount).

I am taking Elementary Statistics this summer and have a TI-83 plus calculator, I did not do very good in algebra but passed. I am thinking of buying the book, does it come with training on how to use the calculator? I was not able to fin the app that says stats?

Thank you, and please let me know I would like to pass this class and I only have a 10 week class

Trish

Trish,

The TI-83 guide walks you through the steps to using the calculator for a wide variety of problems. It comes free with the statistics handbook if you buy it here on the site.

Good luck!

Stephanie

download link not visible. Paid for statistics handbook. 1/28/15

Hello, Glory,

I am resending you the link right now. Please let me know if you don’t get it.

The filling machine used by a dairy company to fill 1kg containers of yoghurt produces output which follows a normal distribution with mean 1030g (slightly more than 1kg) and standard deviation 20g. Suppose that the company can change either the mean or the standard deviation of the filling amount (but not both). If they require the probability of underfilling a container (i.e. contents less than 1000g) to equal 0.05, find (i) the smallest value of the mean; and (ii) the largest value of the standard deviation that satisfies this requirement (in each case to the nearest gram).

Hello, Kate,

Can you post on our homework help forum, please. One of our mods will be happy to help.

I have taken Elementary Statistics /Math 300 through Aleks. And I failed it. This is the last class for my BA degree, and I am worried I will not pass it again. Will your book help me get through this class. I am on SS only and have to pay for this class which is going to hurt me a lot. I want to order you book it looks like it will give me some hope in this class. If I order this how long will it take it to get to me?

Thank you for your time

Mary Ann K

Hi, Mary Ann,

The book is an e-book (actually a collection of 4 books), so it’s an instant download. When I taught statistics, students who used the book tended to get one grade higher, so for those struggling, it often resulted in a pass. You might also want to look at our YouTube channel, which has hundreds of videos to walk you through popular statistics topics. We also have a forum, where you can ask questions if you get stuck.

I wish you the best of luck with passing your class,

Stephanie

Your site’s definition of “variable” (a quantity that has changing values, although better: that could be any of a set of values) is horrible. A variable is a “place holder in a data matrix.” The idea is that you plan out your research project before any data are collected: how many respondents (n), how many variables (v1…vk), & each of the variables’ possible attributes (v1{a1…z1},…, vk{ak…zk}). The upshot of this plan is an empty data matrix (technically referred to as your sample space), which only gets filled in when your sample is drawn. Filling in a data matrix involves n-times-k events, where each set of k events for any individual respondent is random (i.e., it has the same probability as every other such respondent-set in the population). (Since events among respondents are not constrained to be random, associations among events are interpreted as being among variables. This follows because due to one’s random selection process, associations among respondents could only result due to sampling error [i.e., only if the random selection process yielded a peculiar, unrepresentative sample].) So a variable is not a quantity; at best it is a “possible quantity.” And it does not have changing values: Its values are fixed at the moment one’s sample is drawn (at which time it is no longer a random variable, but forms a column of numbers in your data matrix). With respect, your definition does not simplify matters; it leaves the novice with little insight into one of the most fundamental of statistical ideas. Beyond this, I do not see any section of your site devoted to the Central Limit Theorem. Don’t “the rest of us” need to understand this?

Hi, Carl,

Thanks for your comments. I do get hits from people searching for algebra topics as well as statistics. I’ve had questions in the past from people confused about the difference between algebra variables, statistics variables etc., so I wanted the term “variable” to be as general as possible. Most of the people visiting this site are not math majors; they are liberal arts majors struggling to understand statistics, so I try to simplify the terms as much as possible. I fear that putting the definition “a place holder in a data matrix” will completely confuse most liberal arts folks.

On the specific variable posts/pages (i.e.confounding variable ) I do go more in depth.

Here is the CLT page: Central Limit Theorem.

Regards,

Stephanie