What are the potential risks associated with incorrectly assuming that data are MCAR when they are actually MAR?
- Bias in parameter estimates
- Both underestimation of standard errors and bias in parameter estimates
- No potential risks
- Underestimation of standard errors
If data are incorrectly assumed to be MCAR when they are actually MAR, it can lead to both underestimation of standard errors and bias in parameter estimates, leading to inaccurate analyses and conclusions.
You notice that the data from some weather sensors is missing because the sensors malfunctioned when the temperature dropped below a certain level. What type of missing data does this represent?
- MAR
- MCAR
- NMAR
- Not missing data
This would be MAR (Missing at Random) because the missingness is related to an observed data (the temperature). The missing data is not random, but it doesn't depend on the unobserved data itself.
How is the shape of a Normal Distribution usually described?
- Bell-shaped
- Skewed to the left
- Skewed to the right
- Uniformly flat
A Normal Distribution is described as bell-shaped. It is symmetric around the mean, and most of the data falls close to the mean with fewer values further away.
Suppose your machine learning model shows a significant shift in performance when transitioning from the training set to the test set. How could mishandling missing data contribute to this issue?
- It may have caused an imbalance in the data distribution between the sets.
- It may have caused overfitting.
- It may have led to the model learning irrelevant patterns.
- It may have led to underfitting.
If the handling of missing data is not consistent between the training and test sets, it could lead to an imbalance in data distribution between the two sets, causing the model's performance to shift.
What kind of bias might be introduced into a model if missing data is not appropriately addressed?
- All above.
- Confirmation bias.
- Observation bias.
- Sampling bias.
Inappropriate handling of missing data can lead to sampling bias, where the model is trained on a non-representative subset of the data, hence the model's predictions could be biased.
What are the key components to focus on during the 'communicate' step in EDA?
- Cleaning and transforming data
- Ensuring the insights are effectively conveyed to relevant stakeholders
- Only sharing the raw data
- Reordering the EDA steps
During the communication phase of the EDA process, the key focus is to ensure that the insights, findings, or conclusions drawn from the analysis are effectively conveyed to the relevant stakeholders. This might involve presenting the insights in a simple and understandable manner, making use of visualizations, and tailoring the communication to the audience's needs and context.
If a row with at least one missing value is deleted, the process is known as _____.
- Listwise Deletion
- Mean Imputation
- Mode Imputation
- Pairwise Deletion
If a row with at least one missing value is deleted, the process is known as 'listwise deletion'. Although it is a simple method, it can result in loss of valuable information if the missing data is not completely random.
Given a set of data that follows a Binomial Distribution, how would you estimate the parameters of the distribution?
- By applying the Central Limit Theorem
- By computing the mean and standard deviation
- By taking the square root of the data
- By using a chi-squared test
The parameters of a Binomial Distribution can be estimated by computing the mean and standard deviation of the data.
If a distribution is bimodal with two distinct peaks, there may be _____ distinct mode(s).
- None
- One
- Three
- Two
In a bimodal distribution, there are "Two" distinct modes or peaks. Hence, there may be two distinct modes.
You are conducting a study on the annual rainfall in various cities. The data recorded is in millimeters. What type of data is this?
- Continuous data
- Discrete data
- Nominal data
- Ordinal data
Rainfall measurement in millimeters is a continuous variable because it can take on any value within a range.