Equal variance

Different industries have different levels of investment from venture capitalists (VCs). However, if you look at a sample of VC investments and see slightly different average investment amounts, is it reasonable to assume this difference is statistically significant? This is a perfect situation for ANOVA. However, a key condition for ANOVA is equal variance between all groups of samples. In this exercise you'll test for that using the Levene test of equal variance.

A pandas DataFrame of investments of three industries (Biotechnology, Enterprise Software and Health Care) has been loaded for you in investments_df. The packages pandas as pd, NumPy as np, Matplotlib as plt, and the stats package from SciPy have all been loaded as well.

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Foundations of Inference in Python

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Select the funding for each market individually from investments_df using the column names given.
Conduct Levene tests for equal variance between each pair of industries, in the following order: (i) Biotechnology and Enterprise Software, (ii) Biotechnology and Health Care, and (iii) Enterprise Software and Health Care, corresponding to statistic1, statistic2, and statistic3, respectively.
In each case, return a Boolean that indicates whether the null hypothesis of equal variance is rejected.

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# Select each industry separately
biotech_df = ____
enterprise_df = ____
health_df = ____

# Conduct Levene tests for equal variance between funding_total_usd for all pairs of industries
statistic_1, p_value_1 = ____
statistic_2, p_value_2 = ____
statistic_3, p_value_3 = ____

# Print if the p-value is significant at the 5% level
print(____)
print(____)
print(____)

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Foundations of Inference in Python

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In this chapter, we'll explore the relationship between samples and statistically justifiable conclusions. Choosing a sample is the basis of making sound statistical decisions, and we’ll explore how the choice of a sample affects the outcome of your inference.

Exercise 1: Statistical inference and random sampling Exercise 2: Sampling and point estimates Exercise 3: Repeated sampling, point estimates and inference Exercise 4: Sampling and bias Exercise 5: Visualizing samples Exercise 6: Inference and bias Exercise 7: Confidence intervals and sampling Exercise 8: Normal sampling distributions Exercise 9: Calculating confidence intervals Exercise 10: Drawing conclusions from samples

Learn all about applying normality tests, correlation tests, and parametric and non-parametric tests for sound inference. Hypothesis tests are tools, and choosing the right tool for the job is critical for statistical decision-making. While you may be familiar with some of these tests in introductory courses, you'll go deeper to enhance your inferential toolkit in this chapter.

Exercise 1: Normality tests Exercise 2: Testing for normality Exercise 3: Distribution of errors Exercise 4: Fitting a normal distribution Exercise 5: Correlation tests Exercise 6: Testing for correlation Exercise 7: Autocorrelation Exercise 8: Explained variance Exercise 9: Parametric tests Exercise 10: Equal variance

Aktuelle Übung

Exercise 11: Normality of groups Exercise 12: ANOVA Exercise 13: Non-parametric tests Exercise 14: Comparing rankings Exercise 15: Comparing medians

In this chapter, you'll measure and interpret effect size in various situations, encounter the multiple comparisons problem, and explore the power of a test in depth. While p-values tell you if a significant effect is present, they don't tell you how strong that effect is. Effect size measures how strong an effect a treatment has. Master the factors underpinning effect size in this chapter.

Exercise 1: Effect size Exercise 2: Effect size for means Exercise 3: Effect size for correlations Exercise 4: Effect size for categorical variables Exercise 5: Multiple comparisons and corrections Exercise 6: Multiple comparisons problem Exercise 7: Bonferonni-Holm correction Exercise 8: Power of a test Exercise 9: What is power anyway?Exercise 10: Power for experimental design Exercise 11: Computing power and sample sizes

You’ll expand your inferential statistics toolkit further with a look at bootstrapping, permutation tests, and methods of combining evidence from p-values. Bootstrapping will provide you with a first look at statistical simulation. In the lesson meta-analysis, you’ll learn all about combining results from multiple studies. You’ll end with a look at permutation tests, a powerful and flexible non-parametric statistical tool.

Exercise 1: Bootstrapping Exercise 2: Bootstrap confidence intervals Exercise 3: Bootstrapping vs. normality Exercise 4: Combining evidence from p-values Exercise 5: Fisher's method in SciPy Exercise 6: Inference using Fisher's method Exercise 7: Summarizing Fisher's method Exercise 8: Permutation tests Exercise 9: Permutation tests for correlations Exercise 10: Permutation tests and bootstrapping Exercise 11: Analyzing skewed data with a permutation test Exercise 12: Course wrap-up video