## Statistics: When can you use the normal approximation to the binomial distribution?

Tutoring statistics, rules of usage are key. The tutor shares one about when the normal approximation to the binomial distribution can be used. The binomial distribution imagines a series of n trials, each with probability p of success and q=(1-p) …

## Statistics: distribution shape: skew

Tutoring statistics, the concept of skew arises. The tutor gives some brief ideas about skew. The normal distribution isn’t skewed, because its left and right tails are simply mirror images of each other. When a distribution’s left tail is longer …

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## Statistics: what is multiple linear regression?

Tutoring statistics, regression is an important topic. The tutor defines multiple linear regression. Simple linear regression models the dependent variable by a linear connection to the independent: y = a + bx Multiple linear regression models the dependent variable by …

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## Calculator usage, statistics: the amazing Casio fx-991ES PLUS C

Tutoring math, you see all kinds of scientific calculators. The tutor continues to praise the Casio fx-991ES PLUS C. If you were to be marooned on an island with a single calculator…which one would you prefer? The question is absurd, …

## Calculator usage: linear regression on the Casio fx-991ES PLUS C

Tutoring statistics, you cover linear regression. The tutor shows how to get a best-fit line on the Casio fx-991ES PLUS C. Let’s imagine you have the following data x y 10.1 14.2 17.3 19.5 25.4 22.9 40.0 31.8 Furthermore, you’d …

## Statistics: how to calculate standard deviation with the Casio fx-991ES PLUS C

Tutoring statistics, you see lots of great calculators. The tutor shows how to calculate one-var standard deviation on the Casio fx-991ES PLUS C. Let’s imagine you want the standard deviation of the short list of numbers 23, -12, 0, 15, …

## Statistics, spreadsheets: confidence interval for the mean, population standard deviation unknown: CONFIDENCE.T() function on LibreOffice Calc

Tutoring statistics, the tutor is happy to share the CONFIDENCE.T() function from LibreOffice Calc. My last couple of posts (here and here) I’ve talked about confidence intervals for the mean. Yesterday I mentioned finding one using Excel or LibreOffice Calc’s …

## Statistics, spreadsheets: confidence interval for population mean: CONFIDENCE() function on Excel and LibreOffice Calc

Tutoring statistics, you realize how convenient using a spreadsheet can be. In yesterday’s post I mentioned some theoretical points about two-sided confidence intervals for the population mean. On the practical side, if you simply need a confidence interval for the …

## Statistics: confidence interval for the mean (two sided)

Tutoring statistics, confidence intervals are important. A two-sided confidence interval for the population mean is given by sample_mean – (standard_dev/n1/2)*sig_factor, sample_mean + (standard_dev/n1/2)*sig_factor The sig_factor (significance factor) depends on the certainty (confidence level) with which we want the confidence interval …

## Statistics: estimating population size using order statistics

The tutor demonstrates a way to estimate population size from three serial numbers. Imagine you walk into a room after a convention. The participants had been given, not name tags, but number tags. You find three tags: 21, 225, and …

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