lecture three descriptive data

Question 1

what is descriptive statistics ?

Answer 1

Helps summarise and organise data so its easier to understand.

Question 2

what descriptive data measures?

Answer 2

1.center of data- Average like mean, median, and mode.

2.spread of data- Measures of dispersion like range, variance, standard deviation.

3. shape of distribution- how data is spread(symmetrical,skewed,kurtosis)

Question 3

Describe what symmetrical,skewed,kurtosis mean.

Answer 3

1.Symmetrical- no skew equal on both side
2. skewed data- more data on one side, with a long tail on the other side.
3. How sharp or flat the peak of a distribution is.

Question 4

3 reasons why descriptive data is useful :

Answer 4

Helps summarise large datasets.

Make it easy to identify patterns and trends.

Provides a quick snapshot of data without complex calculations.

Question 5

What is a distribution ?

Answer 5

A distribution shows how values in a dataset are spread out or organised.

Question 6

why its useful ?

Answer 6

Helps visualise trends in data

shows if data is skewed.

Helps in predicting future patterns.

Question 7

1 Key measures in descriptive statistics

Answer 7

center of a distribution:

measures the average value in a dataset.
Examples: Mean, Median, Mode.

Question 8

2 Key measures in descriptive statistics

Answer 8

spread of a distribution.

Shows how data is spread out or varies.
Examples: Range,variance,standard deviation.

Question 9

3 Key measures in descriptive statistics

Answer 9

Shape of a distribution.

describe whether the data is symmetrical or skewed.

Includes skewness (asymmetry) and kurtosis (peak sharpness)

Question 10

1.Central tendency(average). Mean

Answer 10

Mean(arithmetic average)

calculated as:

mean= sum of all values/ total number of values.

Question 11

2.central tendency Median

Answer 11

Median(middle value)

the middle value when data is arranged in ascending order.

Question 12

3. central tendency Mode

Answer 12

Mode(most frequent values)

The value that appears the most in a dataset

Question 13

Choosing the right average

Answer 13

shape of distribution-

symmetrical data; mean is best

skewed data; Median is better

Question 14

what is percentiles and quartiles ?

Answer 14

Help divide a dataset into equal parts to help understand how values are spread.

Question 15

percentiles

Answer 15

A dataset is divided into 100 equal sections. Each section is a percentile.
p1=1% to 100

Question 16

Quartiles

Answer 16

Split data into 4 parts.
Q1(25%) lower quartile.
Q2(50%) median
Q3(75%) upper quartile
Q4(100%) maximum value

helps understand how data is spread.