Data Science Interview Questions -II

  1. Q 5: What is overfitting and underfitting?

Answer: Solving the issue of bias and variance is really about dealing with over-fitting and under-fitting. Bias is reduced, and variance is increased in relation to model complexity.
As more and more parameters are added to a model, the complexity of the model rises, and variance becomes our primary concern while bias steadily falls.
Underfitting: The model has not captured the underlying logic of the data, it clusmey and low accuracy.


Q 6 : What is Hypothesis?


Answer:
Hypothesis is a predictive statement, capable of being tested by scientific methods, that relates an independent variable to some dependent variable.
A hypothesis states what we are looking for and it is a proportion which can be put to a test to determine its validity. E.g. Student who receive counselling will show a greater increase in creativity then students not receiving counselling.

Characteristics of Hypothesis:
  • Clear and precise.
  •  Capable of being tested
  • Stated relationship between variables.
  • Limited in scope and must be specific.
  • Stated as for possible in must simple terms so that the same is easy understand by all concerned. But one must remember that simplicity of hypothesis has nothing to do with it’s significance.
  • Consistent with most known facts.
  • Responsive to testing with in a reasonable time. One can’t spend a life time collecting data to test it.
  • Explain what is claims to explain; it should have empirical reference.

Null Hypothesis:
-          It is an assertion that we hold as true unless we have sufficient statistical evidence to conclude otherwise.
-          Null hypothesis is donated by H0
-          If a population mean is equal to hypothesised mean or sample mean, then Hypothesis can be written as

Alternative Hypothesis:
-          The Alternative hypothesis is negative of full hypothesis and is denoted by Ha
-          The alternative Hypothesis can be written as 


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