StatQuest

A paired t-test: is a statistical test used to compare the means from the same group at two different times.

It’s used in scenarios such as:

*When the same subjects are measured twice under two conditions. ( weight before and after a diet program).

*When the same patient is measured using two different medical tests.

Standard Deviation vs Standard Error

Standard Deviation: A measure of the variability of data points within one sample. It’s show how close individual data values are to the mean of the sample. Standard deviation is a descriptive statistic.

Standard Error: An estimate the variability of sample mean across multiple sample drowns from the same population. It’s show how close your sample mean to the true population mean. Standard error is an inferential statistic.

Bonferroni correction : is a technique used in statistics to adjust the significant level when you are making multiple comparisons.

Advantage: control false positives
Disadvantage: increases risk of type II error.

Correlation: is a statistical tool that measure the strength and direction of a relationship between two variables.

Direction:
* positive: one variable increases the other tends to increase.
* Negative: one variable increases the other tends to decrease.
* Zero: no relationship.

Note/ in correlation there’s no cause or effect!

Regression: is a statistical technique that estimates the relationship between dependent variable and independent variable. It’s show the impact of the independent variable on the dependent variable.

Direction: unlike correlation, regression assumes one variable impacts other.

Data collection methods

1- Primary data collection
A-survey
B-Interviews
C-Observations
D-Experiments

2-Secondary data collection
A-Government database
B-NGO database
C- Academic papers

Market Research : A systematic process of collecting, analyzing and interpreting information about target market and customers.
Aim: To inform business strategy, improve products/services , and reduce risk before lunching something new.