Self-tutoring about statistics: the tutor mentions some intriguing ideas (and resources they came from) about degrees of freedom. Degrees of freedom (df) is a concern in calculating statistics, eg., the t or Chi-squared, since the higher the df, the more …
Self-tutoring about the binomial distribution: the tutor mentions a couple of criteria for approximating it to the normal distribution. The binomial, given enough trials, settles into a normal distribution. Yet, how many trials, or what other conditions, might suggest this …
Self-tutoring about statistics: the tutor asks a question. What percent of marriages last 25 years? Thirty-five percent, apparently. That’s in the US, 2011. Source: census.gov
Tutoring statistics, definitions are of interest. The tutor mentions endogeneity. endogeneity: when an explanatory variable affects the error term in a predictable way. An example would be a model that measures the amount of daily sunlight received, but assumes (wrongly) …
Self-tutoring about statistics: the tutor mentions rarefaction. I’ve seen the terms rarefy, rarefied, rarefaction, etc, but never knew what they meant. Today I decided to change that, but it was like opening an overfilled closet where everything jumps out at …
Tutoring statistics, so many inroads are available. The tutor continues about the base rate fallacy. Continuing from my post yesterday, I’ll explore a connection to it: believing what you see, vs not. The base rate fallacy means that people believe …
Statistics: base rate fallacy, part 2: belief vs disbelief Read more »
Tutoring statistics, you encounter day-to-day ideas. The tutor mentions the false-positive paradox. false-positive paradox: In a population where condition A is extremely uncommon, most tests for it that yield “positive” may likely be false. The false-positive paradox is easy to …
Statistics: base rate fallacy, part 1: false-positive paradox Read more »
Tutoring statistics, rules of thumb can be key. The tutor mentions a real-life application of the 68-95-99 rule. With hot, dry weather comes also the job of irrigation, for those who choose to do so. My wife wants a nice …
Tutoring statistics, you might imagine everyday situations. The tutor brings up one. Let’s imagine we have two mile runners. Runner 1, called R1, has mean time 4:45, with standard deviation 10s; R2 has mean time 5:00 with standard deviation 12s. …
Statistics: how often can something “better” be expected to perform better? Read more »
Tutoring stats, you deal with p-values. The tutor shows an Excel connection. In my posts here and here I mention p-values. Example: Using Excel, get a two-tailed p-value for z=2.4 Solution: Using symmetry, it’s best to get the cumulative z-probability …