Page 295 - Data Science class 11
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16.  What is two sampling methods?
              Ans. The two sampling methods are:
                  a. Probability sampling           b. Non-probability sampling
               17.  What is sampling error?
              Ans.  Sampling error is the difference between a population parameter and a sample statistic used to estimate it.
               18.  What is sampling bias?
              Ans.  It is an error-based bias in the way the survey respondents are chosen. This bias occurs when a survey sample is
                  not completely random.
               19.  What does 95% confidence level mean?
              Ans.  a 95% confidence interval is a range of values that you can be 95% certain. With a 95 % confidence interval, you
                  have only 5 percent chance of being wrong.
               20.  What is a sensor?
              Ans.  A sensor is a device that responds to a physical stimulus and transmits a resulting impulse for automatically
                  controlled actuators.
               21.  What are the components of a RStudio?
              Ans.  The components of R Studio are:
                  a. Code Editor         b. Console    c. Environment tab           d. Files tab
               22.  What are the three main components of R program?
              Ans.  variables, comments and keywords
               23.  Name the basic data types of R language?
              Ans.  The basic data types are:
                  a. Numeric             b. Integer    c. Complex    d. Character   e. Logical (Boolean)
               24.  Name the objects in R programming language.
              Ans.  The objects are:
                  a. Vectors             b. Lists      c. Matrices   d. Arrays      e. Factors    f. Data frames
               25.  What is the difference between vector and list objects?
              Ans.  Vector: It is a sequence of elements which contains data of the same data type.
                  List: A list in R is type of R object that contains different types of elements like—numbers, vectors, strings and
                  another list within it.
               26.  What is the use of byrow parameter in a matrix?
              Ans.  It represents a logical clue. When it is set to TRUE, the elements are arranged row wise. By default, this value is
                  set to FALSE.
               27.  What does an array of dimension (4,3,2) refer to?
              Ans.  It refers to two rectangular matrices, each with four rows and 3 columns.
               28.  What is the significance of data frame in R?
              Ans.  A data frame is a table or a two-dimensional array-like structure in which each column contains values of one
                  variable and each row contains one set of values from each column. It is the most common way of storing data
                  in R and most often used for data analysis.
               29.  What does the summary() of a data frame show?
              Ans.  It shows the following details for each and column of a data frame.
                  a. Minimum value       b. 1  quartile  c. Median   d. Mean        e. 3  quartile
                                                                                       rd
                                            st
                  f. Maximum value
               30.  Which library is used for data visualization in r?
              Ans.  ggplot2  library.  It is based on the  ‘Grammar  of Graphics”  which  consists of a  set of rules and  independent
                  components that can be used to represent data is a variety of formats.
               31.  Name some R built-in data sets.
              Ans.  mtcars, iris, ToothGrowth, PlantGrowth, USArrests
               32.  What does the parameter xlab and ylab refer to in the plot()?
              Ans.  xlab refers to the x-axis label and ylab refers to y-axis label.




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