Hypothesis Tests Simplified: The Big Picture of Statistics

Alt-text: A visual representation of the poll conducted about the opinions of Fast Technologies customers about the quality of the hard drive. The large population, which represents all Fast customers, and data was produced from 1082 of these customers by asking them how many stars they would rate the product. In the data set we have 1082 responses, and exploratory data analysis tells us that 65% gave the product 4 stars. Using both probability and inference, we can draw the conclusion that we are 95% sure that the population percentage is within 3% of 65% (i.e. between 62% and 68%).

The Big Picture of Statistics¹ The process of statistics starts when we identify what group we want to study or learn something about. We call this group the population. Note that the word “population” here (and in the entire course) is not just used to refer to people; it is used in the broader statistical […]

Pick-a-Problem: Not given values for µ in 8.1.11

Question: I have hit the wall on a simple problem. I seem to be hitting these more often now. At any rate. 8.1.11, the difference between two means hypothesis test standardized test statistic requires µ1 – µ2. So, how does one calculate this when we are never given a value for μ? I used 0 for […]

Finding Critical Values and Degrees of Freedom

Many students struggle to find critical values of z, t, and Chi-square for hypothesis tests. No matter how often I show them how to use the StatCrunch calculators to do this, they gravitate back to the tables. And make a lot of mistakes. To help a bit, I have created some Excel calculators that should […]

Single-sample Hypothesis Test for a Proportion

Consider the following problem statement: An article in an online magazine states that 40% of home buyers found their real estate agent through referrals by a friend. However, a professor in a local college sampled 1000 home buyers and found that 426 chose an agent recommended by a friend. Does the data refute the claim […]